JP2005135825A - Control device for fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent imparting an adverse effect to a fuel cell, by appropriately eliminating air from deionized water system when starting the fuel cell system. <P>SOLUTION: Circulating paths 3 and 4 for circulating the deionized water to the fuel cell 1 via a deionized water pump 5 are provided. When the fuel cell system is stopped, air pressure is introduced and the deionized water in the fuel cell 1, the deionized water in the circulating paths 3 and 4 and the deionized water, in constituting parts of the circulating paths 3 and 4, are recovered to a deionized water tank 2 in the fuel cell system. A circulated water quantity control means 20 is provided for controlling the quantity of flow of the circulating deionized water, according to the state of operation of the fuel cell system. When the fuel cell system is started, the quantity of flow of the deionized water is controlled by the control means 20 to be increased to more than the quantity of flow of the deionized water in idle operation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a control device for a fuel cell system.

The fuel cell system collects pure water in the system to prevent freezing when operation is stopped, and starts circulation of pure water at the start of operation (for example, Patent Document 1).
JP-A-11-273705

  The pure water in the fuel cell system has a small circulation amount during idle operation with a small amount of power generated by the fuel cell and a small amount of gas supply.

  Therefore, when starting the system, the circulating pure water was started at a low flow rate such as an idle flow rate, so that the air in the pure water system pipes and components was not sufficiently removed, and there was a risk of air accumulation. was there.

  If air enters a fuel cell that is generating electricity, it may affect the fuel cell.

  An object of the present invention is to solve such a problem by accurately removing pure water air when the fuel cell system is started.

  The present invention has a circulation path for circulating pure water to a fuel cell via a pure water pump, and when the fuel cell system is stopped, air pressure is introduced to supply the pure water in the fuel cell and the circulation path. In the fuel cell system that collects pure water in the components of the circulation path and pure water in the components of the circulation path into the pure water tank, circulating water amount control means for controlling the flow rate of the pure water circulated according to the operating state of the fuel cell system is provided. Prepare. The circulating water amount control means controls the flow rate of pure water to be larger than the flow rate of pure water during idle operation when the fuel cell system is started.

  According to the present invention, pure water can be accurately filled in the fuel cell, the circulation path, and the components of the circulation path, and no air pool is generated in the circulation path and the components of the circulation path. Therefore, it is possible to prevent air from being mixed into the fuel cell that is generating power, thereby adversely affecting or damaging the fuel cell.

  Hereinafter, a first embodiment will be described with reference to the drawings.

  FIG. 1 shows the configuration of a pure water system of a fuel cell system.

  In FIG. 1, 1 is a fuel cell (a stack is formed by assembling a predetermined number of single cells of a fuel cell), 2 is a pure water tank for storing pure water, and 3 is a supply side of a circulation path for circulating pure water A passage 4 is a return-side passage.

  The inlet portion of the supply side passage 3 is disposed at the bottom of the pure water tank 2.

  In the middle of the supply side passage 3, a pure water pump 5 is installed in the vicinity of the pure water tank 2, and a foreign matter filter 6 for removing foreign matters and an ion filter 7 for improving the conductivity of pure water are installed downstream thereof. ing.

  An outlet portion of the supply side passage 3 is connected to an inlet of a pure water passage provided in the fuel cell 1.

  An inlet portion of the return side passage 4 is connected to an outlet of a pure water passage provided in the fuel cell 1.

  The exit portion of the return side passage 4 is disposed in the pure water tank 2.

  Pure water is introduced and circulated in the pure water flow path inside the fuel cell 1 for humidification of hydrogen gas and air (oxidant gas) and for cooling the fuel cell 1.

  On the other hand, the pure water tank 2 is provided with an air introduction line 10 for introducing high-pressure air into the tank 2 via the air valve 8 to increase the internal pressure and sending priming water to the pure water pump 5. . The supply-side passage 3 between the pure water pump 5 and the foreign matter filter 6 is connected to a priming valve 11 for opening the downstream of the pure water pump 5 when priming water to the pure water pump 5.

  In the middle of the return side passage 4, the return side passage 4, the fuel cell 1, the supply side passage 3, the ion filter 7, the foreign matter filter 6, and the pure water pump 5 are purged with pure water. A purge air introduction line 13 for introducing high-pressure air through the purge valve 12 is connected to the passage 4. A shut-off valve 14 for shutting off the passage 4 is provided in the return side passage 4 immediately downstream of the connection portion of the purge air introduction line 13.

  Predetermined high-pressure air is sent to the air introduction line 10 and the purge air introduction line 13 from a compressor or an air tank (not shown).

  The pure water tank 2 is a pure water system in order to accurately purge the pure water in each of the return side passage 4, the fuel cell 1, the supply side passage 3, the ion filter 7, the foreign matter filter 6, and the pure water pump 5. Arranged at the lowest position. In addition, the fuel cell 1, the ion filter 7, the foreign matter filter 6, and the pure water pump 5 are disposed at a higher level in this order, and the pure water pump 5 is disposed at a higher level than the water level when the pure water tank 2 is full.

  In the figure, reference numeral 20 denotes a controller for controlling the pure water pump 5 and the valves 8, 11, 12, 14.

  During normal operation of the fuel cell system, the controller 20 closes the air valve 8, the priming valve 11, and the purge valve 12, opens the shutoff valve 14, drives the pure water pump 5, and circulates pure water.

  The pure water circulates through the pure water tank 2 → the pure water pump 5 → the foreign matter filter 6 → the ion filter 7 → the fuel cell 1 → the cutoff valve 14 → the pure water tank 2.

  The amount of pure water required is adjusted by changing the output of the pure water pump 5 according to the output of the fuel cell 1 or the like.

  Next, the control contents of the controller 20 when the fuel cell system is stopped will be described based on the flowchart of FIG.

  When the fuel cell system is stopped, the pure water in the fuel cell 1 and the pure water in the circulation path and each component (ion filter 7, foreign matter filter 6, pure water pump 5) are used in a pure water tank for freezing. It is necessary to return to 2.

  In steps S1 and S2, after the pure water pump 5 is stopped, the shutoff valve 14 of the return side passage 4 of the pure water path (circulation route) is closed, and the purge valve 12 of the purge air introduction line 13 is opened.

  In step S3, time measurement is started.

  When the purge valve 12 is opened and predetermined high-pressure air is introduced from the purge air introduction line 13 into the return side passage 4, pure water in the return side passage 4 upstream from the air introduction position of the purge air introduction line 13 is generated by the air pressure. Is pushed out in the direction opposite to the shutoff valve 14, so that pure water flows through the fuel cell 1 and the supply-side passage 3 to the pure water tank 2.

  In step S4, it is checked whether or not a predetermined time E (time required for purifying the pure water system) has elapsed.

  In steps S5 and S6, when the predetermined time E has elapsed, the shutoff valve 14 is opened and the purge valve 12 is closed.

  For this reason, pure water downstream of the shutoff valve 14 also flows to the pure water tank 2, and a state in which most pure water pure water is collected in the pure water tank 2.

  Therefore, even when the ambient temperature becomes below freezing point, the fuel cell 1, the circulation path, and each component do not freeze.

  Next, the control content of the controller 20 at the start of the fuel cell system will be described based on the flowchart of FIG.

  In step S <b> 11, the air valve 8 of the air introduction line 10 is opened, and predetermined high-pressure air is introduced into the pure water tank 2.

  In steps S12 and S13, the shutoff valve 14 of the return side passage 4 of the pure water path (circulation path) is closed and the priming valve 11 is opened.

  The pure water pump 5 is drained with pure water when the fuel cell system is stopped. Therefore, it is necessary to send priming water to activate the pure water pump 5, and the air valve 8 of the air introduction line 10 is opened to open the pure water tank. A predetermined high-pressure air is introduced into 2 to increase the internal pressure of the pure water tank 2. By opening the priming water valve 11, the downstream of the pure water pump 5 is brought to almost atmospheric pressure, and the shutoff valve 14 is closed, whereby the pure water in the pure water tank 2 is purified by the increase in the internal pressure of the pure water tank 2. 5 to complete the priming of the pure water pump 5.

  In step S14, after the priming is completed, the pure water pump 5 is started.

  In this case, the discharge flow rate of the pure water pump 5, that is, the pure water flow rate for circulating the pure water system, is higher than the pure water flow rate during idle operation, and to a set flow rate A that is higher than the minimum flow rate required for venting the pure water system. Thus, the pure water pump 5 is controlled.

  FIG. 4 shows the control characteristics of the pure water flow rate for circulating the pure water system.

  The flow rate of pure water to be circulated in the fuel cell 1 is changed according to the output of the fuel cell 1 and is controlled so as to circulate the pure water flow rate proportional to the output from idle to rated.

  The minimum flow rate required for venting the pure water system is determined by the pure water flow path of the fuel cell 1, the pipe diameter and length of the pure water path, the volume of the components of the pure water path, the pressure loss, and the like.

  The set flow rate A at the start of the fuel cell system is set between the minimum flow rate required for bleeding and the rated flow rate. In this case, it is desirable that the set flow rate A is as high as possible.

  FIG. 5 shows the PQ performance of the pure water pump 5.

  The pure water pump 5 controls the flow rate by PWM (pulse width modulation) control. The thin solid line shown in the figure is an equal DUTY line, and the thick solid line indicates the pressure loss of the pure water system. The amount of pure water that actually flows is the value of the intersection of the PQ performance line of the pure water pump 5 determined from the DUTY value that is the control signal and the pressure loss of the pure water system.

  In step S15, time measurement is started with respect to the start of activation of the pure water pump 5.

  In steps S16 and S17, the priming valve 11 is closed and the shutoff valve 14 of the return side passage 4 of the pure water path is opened.

  In step S18, it is determined whether or not a predetermined time F (time required for venting the pure water system) has elapsed since the start of starting the pure water pump 5.

  In step S19, when the predetermined time F has elapsed from the start of starting the pure water pump 5, the circulating pure water flow rate is returned to the pure water flow rate during idle operation.

  After the start-up process is completed, the pure water flow rate is controlled from the idle flow rate to the rated flow rate while maintaining a predetermined differential pressure from the gas (hydrogen gas, air) pressure according to the power generation request of the fuel cell system. .

  Thus, when starting the pure water circulation when starting the fuel cell system, the pure water is circulated at the set flow rate A. Since this set flow rate A is higher than the idle flow rate and the minimum flow rate required for venting, the fuel cell 1, the circulation path pipe, and the components of the circulation path can be filled with pure water accurately, and the circulation path pipe In addition, no air pool is generated in the components of the circulation path.

  Therefore, air does not enter the fuel cell 1 during power generation and the pure water does not stay in the plurality of parallel pure water flow paths installed between the reaction membranes of the fuel cell 1, which adversely affects or damages the power generation of the fuel cell 1. Will not be given.

  6 and 7 show a second embodiment.

  In this method, a pressure sensor 30 for detecting the pressure of pure water at the outlet of the fuel cell 1 is provided in the return side passage 4 of the pure water path (circulation route) to control the deaeration of the pure water system.

  When starting the fuel cell system, as shown in FIG. 7, in step S <b> 21, the air valve 8 of the air introduction line 10 is opened to introduce predetermined high-pressure air into the pure water tank 2.

  In steps S22 and S23, the shutoff valve 14 of the return side passage 4 of the pure water path (circulation route) is closed and the priming valve 11 is opened.

  In step S24, after the priming is completed, the pure water pump 5 is started.

  The discharge flow rate of the pure water pump 5, that is, the pure water flow rate that circulates the pure water system, is higher than the pure water flow rate during idle operation, and is higher than the minimum flow rate required for venting the pure water system (see FIG. The pure water pump 5 is controlled as shown in FIG.

  In steps S25 and S26, the priming valve 11 is closed and the shutoff valve 14 of the return side passage 4 of the pure water path is opened.

  In step S27, the pressure detected by the pressure sensor 30 is compared with a predetermined pressure D.

  The detected pressure of the pressure sensor 30 at the outlet of the fuel cell 1 is determined by the relationship between the pressure loss downstream of the pressure sensor 30 determined by the piping diameter and length of the return side passage 4 and the pure water flow rate. Therefore, if the predetermined pressure D is set based on the pressure loss downstream of the pressure sensor 30 at the set flow rate A when the downstream of the fuel cell 1 is filled with pure water, the detected pressure of the pressure sensor 30 is the predetermined pressure. When D is exceeded, it can be determined that the pure water system is filled with pure water.

  In step S28, when the pressure detected by the pressure sensor 30 exceeds the predetermined pressure D, the circulating pure water flow rate is returned to the pure water flow rate during idle operation.

  In this way, pure water can be accurately filled in the fuel cell 1, the circulation path piping, and the circulation path components, and the occurrence of an air pool in the circulation path piping and the circulation path components. Can be avoided appropriately.

  FIG. 8 shows a third embodiment.

  This controls the flow rate when filling pure water into pure water in a stepwise manner.

  When starting the fuel cell system, as shown in FIG. 8, in step S <b> 31, the air valve 8 of the air introduction line 10 is opened to introduce predetermined high-pressure air into the pure water tank 2.

  In steps S32 and S33, the shutoff valve 14 of the return side passage 4 of the pure water path (circulation path) is closed, and the priming valve 11 is opened.

  In step S34, after the priming is completed, the pure water pump 5 is started.

  In this case, the pure water pump 5 is controlled so that the discharge flow rate of the pure water pump 5, that is, the pure water flow rate for circulating the pure water system, is set to a high set flow rate B (corresponding to the rated flow rate in FIG. 5).

  Step S35 starts time measurement.

  In steps S36 and S37, the priming valve 11 is closed, and the shutoff valve 14 of the return side passage 4 of the pure water path is opened.

  In step S38, it is determined whether a predetermined time G, that is, a supply time of pure water at the set flow rate B has elapsed.

  In step S39, when the predetermined time G has elapsed, the pure water flow rate to be circulated is controlled to a set flow rate C (corresponding to the set flow rate A in the above-described form) that is smaller than the set flow rate B.

  In step S40, it is determined whether a predetermined time H, that is, whether the supply time of pure water at the set flow rate C has elapsed.

  In step S41, when the predetermined time H has elapsed, the pure water flow to be circulated is returned to the pure water flow during idle operation.

  At the start of the fuel cell system, pure water is initially flowed at a large set flow rate B.

  Two filters 6 and 7 are installed in the circulation path upstream of the fuel cell 1. Therefore, pure water is quickly filled into both the filters 6 and 7 by flowing pure water at a large set flow rate B. it can. Since the supply of pure water at the set flow rate B ends in a predetermined time G, the pure water does not reach the fuel cell 1 and the pure water pressure in the fuel cell 1 is not extremely increased.

  When the supply of pure water at the set flow rate B is finished, the pure water is then flowed at the set flow rate C with the flow rate decreased.

  Therefore, it is possible to accurately fill the fuel cell 1 and the return side passage 4 of the circulation path with pure water.

  Thereafter, when the predetermined time H has passed, the flow rate is returned to the pure water flow rate during idle operation (the control may be based on the pressure detected by the pressure sensor 30 as in the second embodiment).

The relationship between the set flow rate B and the set flow rate C is
Set flow rate B> Set flow rate C
Maximum flow rate at which differential pressure control with the gas pressure of the fuel cell 1 is established
≧ Set flow rate C> minimum flow rate required for air bleeding.

  In this way, the pure water can be filled in the fuel cell 1, the circulation path piping, and the circulation path components more accurately and in a short time, and in particular, in the circulation path components upstream of the fuel cell 1. A more appropriate air can be vented. Therefore, the fuel cell system can be started up in a shorter time.

  It can be applied to fuel cells for vehicles and other vehicles.

It is a block diagram of the pure water system of 1st Embodiment. It is a control flowchart. It is a control flowchart. It is a control characteristic figure of a pure water flow rate. It is a PQ performance characteristic figure of a pure water pump. It is a block diagram of the pure water system of 2nd Embodiment. It is a control flowchart. It is a control flowchart of a 3rd embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Pure water tank 3 Supply side passage 4 Return side passage 5 Pure water pump 6 Foreign matter filter 7 Ion filter 8 Air valve 10 Air introduction line 11 Nominal valve 12 Purge valve 13 Purge air introduction line 14 Shut off valve 20 Controller 30 Pressure sensor

Claims (4)

The fuel cell has a circulation path for circulating pure water through a pure water pump,
In a fuel cell system that introduces air pressure when the fuel cell system is stopped and collects pure water in the fuel cell, pure water in the circulation path, and pure water in the components of the circulation path in a pure water tank. ,
Comprising a circulating water amount control means for controlling the flow rate of pure water circulating according to the operating state of the fuel cell system;
The control apparatus for a fuel cell system, wherein the circulating water amount control means controls the flow rate of pure water to be greater than the flow rate of pure water during idle operation when the fuel cell system is started.   2. The fuel cell system according to claim 1, wherein the circulating water amount control unit returns the flow rate during idle operation when a predetermined time has elapsed after starting the increase control when the fuel cell system is started. Control device. A pressure sensor is provided to detect the pressure of pure water at the fuel cell outlet,
2. The fuel cell according to claim 1, wherein the circulating water amount control means returns the flow rate during idle operation based on a detected pressure of a pressure sensor after starting the increase control when the fuel cell system is started. System control unit.   4. The fuel cell system control device according to claim 2, wherein the increase control is performed to increase the increase range for an initial fixed time period and then decrease the increase range to a predetermined increase value. 5. .

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