JP5086740B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system including a fuel cell warm-up means.

Various fuel cell systems have been proposed as starting means at low temperatures. For example, when starting the fuel cell from a low temperature (particularly below freezing point), in order to promote warm-up of the fuel cell, the supply amount or supply pressure of the cooling water circulating through the fuel cell is adjusted, or external heating means The warm-up promotion control is performed until the temperature of the fuel cell becomes equal to or higher than a predetermined temperature due to heating or the like (see Patent Document 1).
Japanese Patent Laying-Open No. 2003-151597 (paragraphs 0033 to 0039, FIG. 2)

  However, in a conventional fuel cell system, if the system temperature at startup is equal to or lower than a predetermined temperature (below freezing point), the fuel cell warm-up completion determination is performed using the same determination threshold (such as the temperature of the fuel cell). It was. For this reason, depending on the system temperature at the time of startup, there is a possibility that the warm-up completion determination is too early and power generation stability is deteriorated, or conversely the warm-up completion determination is too late and energy is wasted.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a fuel cell system that can appropriately set the determination timing of completion of warm-up of the fuel cell.

According to a first aspect of the present invention, there is provided a fuel cell that generates power by being supplied with an oxidant gas and a fuel gas , a radiator that radiates the refrigerant warmed by the fuel cell, and between the fuel cell and the radiator. A refrigerant circulation pump that circulates the refrigerant, an oxidant gas supply means that supplies an oxidant gas to the cathode of the fuel cell, a back pressure valve that adjusts the pressure of the cathode of the fuel cell, and a temperature of the fuel cell And a warm-up promotion control unit that performs control so as to promote warm-up of the fuel cell, and a warm-up completion determination unit that determines completion of warm-up of the fuel cell. In the fuel cell system that performs warm-up promotion control by the warm-up promotion control unit until the warm-up completion determination unit determines that the warm-up is completed, the temperature at the time of startup of the fuel cell detected by the temperature detection means Based on There are, the fuel warm-up completion determination threshold setting unit that temperature to set the warm-up completion determination threshold as low as warm-up completion determination is delayed battery further possess at startup, the warm-up facilitating control unit, Compared with the case where warm-up is not promoted, the refrigerant circulation pump is controlled to reduce the flow rate of the refrigerant supplied to the fuel cell, and the oxidant gas supply means is controlled to supply the cathode of the fuel cell. The temperature of the fuel cell detected by the temperature detecting means is at least one of increasing the flow rate of the oxidant gas and increasing the pressure of the cathode of the fuel cell by controlling the back pressure valve. Is determined to be complete by the warm-up completion determination unit when the temperature reaches a predetermined temperature that is the warm-up completion determination threshold set by the warm-up completion determination threshold setting unit .
According to a second aspect of the present invention, there is provided a fuel cell that generates power by being supplied with an oxidant gas and a fuel gas , a radiator that radiates a refrigerant warmed by the fuel cell, and a gap between the fuel cell and the radiator. A refrigerant circulation pump that circulates the refrigerant, an oxidant gas supply means that supplies an oxidant gas to the cathode of the fuel cell, a back pressure valve that adjusts the pressure of the cathode of the fuel cell, and a temperature of the fuel cell And a warm-up promotion control unit that controls to promote warm-up of the fuel cell, and a warm-up completion determination unit that determines completion of warm-up of the fuel cell. In the fuel cell system that performs warm-up promotion control by the warm-up promotion control unit until the completion determination unit determines warm-up completion, based on the temperature at the time of startup of the fuel cell detected by the temperature detection means, Warm up Includes a warm-up completion determination threshold setting unit that sets a completion determination threshold, the warm-up completion determination threshold setting unit, the temperature of the fuel cell is set high lower the warm-up completion determination threshold value in the boot, the warm-up The acceleration control unit controls the refrigerant circulation pump to reduce the flow rate of the refrigerant to be supplied to the fuel cell, and controls the oxidant gas supply means, as compared with the case where the warm-up is not promoted. At least one of increasing the flow rate of the oxidant gas supplied to the cathode of the fuel cell and increasing the pressure of the cathode of the fuel cell by controlling the back pressure valve, detected by the temperature detecting means wherein it is determined that warm-up is completed by warming up completion determination section when the temperature of the fuel cell has reached a predetermined temperature is the warming up completion determination threshold set by the warming up completion determination threshold setting unit And features.
The radiator, the refrigerant circulation pump, and the oxidant gas supply means correspond to a radiator, a water pump, and an air compressor in the embodiments described later.

According to each invention, since the threshold value for ending warm-up is changed based on the temperature of the fuel cell at startup, the warm-up time can be set to an appropriate time, and energy for promoting warm-up can be set. It is possible to prevent problems such as wasteful use and end of warm-up at an early stage even though warm-up has not been completed (although warm-up is still necessary). The temperature of the fuel cell includes not only the temperature of the fuel cell itself but also a temperature that can be substituted around the fuel cell. The completion of warm-up includes the meaning that no further warm-up is required.
In addition, the power generation stability improves as the temperature of the fuel cell rises. That is, since the power generation stability can be grasped based on the temperature of the fuel cell, the temperature of the fuel cell is used as the warm-up completion determination threshold, and the warm-up completion determination threshold is further set to the value of the fuel cell at startup. By determining the temperature, it is possible to accurately determine whether or not the fuel cell is in a stable state.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel cell system which can set appropriately the judgment timing of the warming-up completion of a fuel cell can be provided.

  FIG. 1 is an overall configuration diagram showing a fuel cell system of the present embodiment, FIG. 2 is a flowchart showing start-up control, and FIG. 3 is a map in the case where an integrated current value is used as a warm-up completion determination threshold parameter. The fuel cell system 1 of the present embodiment may be applied to a power supply system for vehicles, ships, and aircraft, or may be applied to a stationary power supply system for home use.

  As shown in FIG. 1, the fuel cell system 1 of this embodiment includes a fuel cell 10, an anode system 20, a cathode system 30, a cooling system 40, a control system 50, and the like.

  The fuel cell 10 has, for example, a structure in which a plurality of unit cells each composed of a membrane electrode assembly in which a solid polymer electrolyte membrane is sandwiched between an anode and a cathode containing a catalyst are sandwiched between a pair of conductive separators. Become. The separator has a groove (flow path) through which hydrogen (reactive gas, fuel gas) flows, a groove (flow path) through which air (reactive gas, oxidant gas) flows, and a groove (flow path) through which refrigerant flows. Etc. are formed. When hydrogen is supplied to the anode and air is supplied to the cathode, power generation is performed by an electrochemical reaction between hydrogen and oxygen in the air.

  The anode system 20 is a system that supplies and discharges hydrogen to and from the anode of the fuel cell 10, and includes a hydrogen tank 21, a hydrogen cutoff valve 22, and the like. The hydrogen tank 21 can be filled with high-purity hydrogen at a very high pressure. The hydrogen cutoff valve 22 is an electromagnetic valve that is opened and closed by a control device 51 described later, and is provided in the vicinity of the outlet of the hydrogen tank 21.

  The hydrogen cutoff valve 22 is connected to the hydrogen tank 21 via a pipe 23a, and is connected to the anode inlet of the fuel cell 10 via a pipe 23b. The anode outlet of the fuel cell 10 is connected to one end of the pipe 23c. Although not shown in the figure, the anode system 20 has a circulation flow path for recirculating the unreacted hydrogen discharged from the anode of the fuel cell 10 back to the inlet of the anode of the fuel cell 10, and hydrogen when shut off. A purge valve that circulates and discharges hydrogen out of the system when the valve is opened is provided.

  The cathode system 30 is a system that supplies and discharges air to and from the cathode of the fuel cell 10, and includes an air compressor 31, a back pressure valve 32, and the like. The air compressor 31 includes a supercharger that is driven by a motor. The back pressure valve 32 is configured by a butterfly valve or the like that can adjust the opening, and can adjust the pressure of the cathode of the fuel cell 10.

  The air compressor 31 is connected to the cathode inlet of the fuel cell 10 via a pipe 33a. The cathode outlet of the fuel cell 10 is connected to one end of the pipe 33b.

  The cooling system 40 includes a radiator 41, a water pump (W / P) 42, pipes 43a, 43b, 43c, and the like. The radiator 41 has a function of radiating heat to the refrigerant warmed by the fuel cell 10. The water pump 42 has a function of circulating the refrigerant, and the rotation speed of the motor is controlled by the control device 51 so that the flow rate of the refrigerant increases and decreases. The refrigerant outlet of the radiator 41 is connected to the refrigerant inlet of the fuel cell 10 via a pipe 43a, and the refrigerant outlet of the fuel cell 10 is connected to the water pump 42 via a pipe 43b. The refrigerant inlet of the radiator 41 is connected to the water pump 42 via a pipe 43c.

  The control system 50 includes a control device 51, a temperature sensor 52, a current sensor 53, a voltage sensor 54, and the like. The control device 51 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Randam Access Memory), various interfaces, an electronic circuit, and the like. The temperature sensor 52 has a function of detecting the temperature of the fuel cell 10. The current sensor 53 has a function of detecting a current value extracted from the fuel cell 10. The voltage sensor 54 has a function of detecting a voltage value applied to the entire fuel cell 10.

  In addition, the control device 51 includes a warm-up promotion control unit 51a, a warm-up completion determination unit 51b, a warm-up completion determination threshold setting unit 51c, and an integrated power generation amount calculation unit 51d.

  The warm-up promotion control unit 51a reduces the flow rate of the refrigerant by decreasing the rotation speed of the water pump 42 at the time of starting at a low temperature (for example, below freezing point), and increases the rotation speed of the air compressor 31 to increase the flow rate of the cathode system 30. The warming-up promotion control is performed by increasing the amount of pressure, increasing the pressure of the cathode system 30 by reducing the opening of the back pressure valve 32, or a combination thereof.

  The warm-up completion determination unit 51b performs control to determine whether or not the warm-up of the fuel cell 10 has been completed. The determination of the warm-up completion is determined by whether or not the warm-up completion determination threshold set by the warm-up completion determination threshold setting unit 51c described later has been reached.

  The warm-up completion determination threshold value setting unit 51c sets a warm-up completion determination threshold value for determining the warm-up completion based on the temperature at the time of startup of the fuel cell 10. That is, the warm-up completion determination threshold is set higher as the temperature of the fuel cell 10 at startup is lower. The temperature of the fuel cell 10 is not limited to the temperature directly measured inside the fuel cell 10. For example, the anode outlet temperature of the fuel cell 10, the cathode outlet temperature of the fuel cell 10, the refrigerant of the fuel cell 10 It may be a temperature estimated from the outlet temperature. In the following description, these temperatures are collectively referred to as a system temperature.

  The integrated power generation amount calculation unit 51 d calculates an integrated value of current (integrated current value) from the start of power generation when the fuel cell 10 is started up, using a detection value obtained from the current sensor 53. Note that the integrated power generation amount calculation unit 51d is not limited to the one calculated by the integrated current value, and uses each detection value from the current sensor 53 and the voltage sensor 54 from the start of power generation when the fuel cell 10 is started. May be calculated from the integrated value (integrated power value) of the power (current × voltage) of the current or may be calculated from the power generation time from the start of power generation.

  Next, start control of the fuel cell system 1 of the present embodiment will be described with reference to FIG. 2 and FIG. When the operation of the fuel cell system 1 is stopped, the hydrogen cutoff valve 22 is closed and the air compressor 31 and the water pump 42 are stopped.

  As shown in FIG. 2, for example, when the ignition switch (IG SW) is turned on by the driver, in step S100, the control device 51 determines whether or not to start below freezing. Whether or not to start below-freezing is determined based on the system temperature or the outside air temperature (a sensor is not shown), and it is determined that the below-freezing start is performed when the system temperature or the outside air temperature is, for example, below freezing. Whether or not to start below freezing is not limited to the determination based only on the temperature at the time of startup, but may be determined with reference to the temperature when the operation of the fuel cell system 1 is stopped. That is, even if the temperature at the time of start-up is not below the freezing point, if the temperature at the time of operation stop is below the freezing point, there is a possibility that the inside of the fuel cell 10 may be frozen. preferable.

  If it is determined in step S100 that the sub-freezing start is performed (Yes), the control device 51 sets a warm-up completion determination threshold value in the fuel cell 10 in step S110. The warm-up completion determination threshold is set based on the system temperature at startup (when the IG SW is ON), and the warm-up completion determination threshold increases as the system temperature at startup decreases (determination of warm-up completion). Is set to be delayed). Moreover, this step S110 is equivalent to the process which the warming-up completion determination threshold value setting part 51c in this embodiment implements.

  The warm-up completion determination threshold is set based on the map of FIG. Since the integrated current amount (integrated power generation amount) has a correlation with the heat generation amount of the fuel cell 10, it is possible to approximate the heat generation amount necessary for de-icing the fuel cell 10 with the integrated current amount. Therefore, as shown in FIG. 3, when the system temperature at startup is high, the warm-up completion determination threshold value (predetermined integrated current amount) in the warm-up completion determination integrated current value is set low, and the system temperature at startup is When it is low, the warm-up completion determination threshold is set high.

  The case where the accumulated current amount is used as the warm-up completion determination threshold has been described as an example. However, the present invention is not limited to this. For example, from the time when the fuel cell 10 is started (when the ignition switch is turned on). May be used, or power generation time may be used.

  In step S120, the control device 51 performs below-freezing start control. The below-freezing start control is control for promoting warm-up of the fuel cell 10. For example, the flow rate of the refrigerant supplied to the fuel cell 10 is decreased by decreasing the rotational speed of the motor of the water pump 42, The flow rate of air supplied to the cathode of the fuel cell 10 is increased by increasing the rotation speed of the motor, or the pressure of the cathode of the fuel cell 10 is increased by reducing the opening of the back pressure valve 32. That is, the cooling capacity of the fuel cell 10 is reduced by reducing the flow rate of the refrigerant, and the fuel cell 10 is warmed by the high-temperature compressed air from the air compressor 31 by increasing the flow rate of the air, and the back pressure valve 32 is opened. By reducing the degree, the reaction between oxygen and hydrogen in the air is promoted, the amount of heat generated by the fuel cell 10 is increased, and the warm-up of the fuel cell 10 is promoted. Note that the below-freezing start control may be performed in any one of the above examples, or may be performed in combination. This step S120 corresponds to the process performed by the warm-up promotion control unit 51a in the present embodiment.

  In step S <b> 130, the control device 51 starts power generation by starting supply of a generated current (generated power) to an external load (not shown). The external load includes the air compressor 31 and the water pump 42.

  In step S140, the control device 51 determines whether or not the current integrated power generation amount calculated by the integrated power generation amount calculation unit 51d is equal to or greater than the warm-up completion determination threshold (predetermined integrated current value) set in step S110. Determine whether. In addition, this step S140 is equivalent to the process which the warming-up completion determination part 51b in this embodiment implements. In step S140, if the control device 51 determines that the warm-up completion determination threshold is not exceeded (No), it repeats the process of step S140, and if it is determined that the warm-up completion determination threshold is exceeded (Yes) ), The process proceeds to step S150.

  In step S150, the control device 51 determines that the warm-up has been completed (determines that no further warm-up is necessary), and cancels the below-freezing-point start control that was started in step S120. That is, the rotational speed of the water pump 42 is increased to return the flow rate of the refrigerant to the normal operation state, and the rotational speed of the air compressor 31 is decreased to decrease the flow rate of the air supplied to the cathode to the normal operation state. Then, the opening of the back pressure valve 32 is widened to reduce the air pressure to return to the normal operation state.

  In step S160, the control device 51 shifts to normal power generation. In step S170, the control device 51 determines whether power generation is in progress. Note that whether or not power generation is in progress is determined by turning off the ignition switch (IG SW). If the controller 51 determines in step S170 that power generation is still in progress (Yes), it returns to step S160 to continue normal power generation, and if it determines that power generation is not in progress (No), Exit.

  In step S100, if control device 51 determines not to start below freezing (No), it proceeds to step S160 and immediately performs normal power generation.

  As described above, according to the fuel cell system 1 of the present embodiment, the warm-up completion determination threshold is changed based on the temperature (system temperature) of the fuel cell 10 at the time of start-up. It becomes possible to set to a long time. As a result, waste of energy (hydrogen) for promoting warm-up due to a delay in determining whether warm-up is complete, and warm-up is performed even though warm-up has not been completed (although warm-up is necessary). It is possible to prevent problems such as termination at an early stage.

  Further, according to the present embodiment, since the warm-up completion determination threshold value is set based on the integrated power generation amount, it is possible to accurately perform the de-icing determination inside the fuel cell 10 and the warm-up completion of the fuel cell 10 is completed. Judgment can be made with high accuracy.

  In the present embodiment, the case where the integrated current value (integrated power generation amount) is used as a parameter for the warm-up completion determination threshold has been described as an example (see FIG. 3), but as shown in FIG. You may set based on the map at the time of using system temperature as a parameter of a completion judgment threshold value. That is, as shown in FIG. 4, when the system temperature at startup is high, the warm-up completion determination system temperature (predetermined system temperature, predetermined temperature) in the warm-up completion determination system temperature is set low, and the system temperature at startup Is low, the warm-up completion determination threshold is set high.

  In this way, the system temperature is used as a parameter for the warm-up completion determination threshold value of the fuel cell 10, and further, the warm-up completion determination threshold value (predetermined system temperature) is determined based on the system temperature at the time of start-up. It is possible to accurately determine whether is in a stable state. This is because if the temperature of the fuel cell 10 (system temperature) rises, the power generation stability also improves.

It is a whole lineblock diagram showing the fuel cell system of this embodiment. It is a flowchart which shows starting control. It is a map at the time of using an integrated current value as a parameter of a warm-up completion determination threshold value. It is a map at the time of using system temperature as a parameter of warm-up completion judgment threshold value.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell system 10 Fuel cell 31 Air compressor 42 Water pump 51 Control apparatus 51a Warm-up promotion control part 51b Warm-up completion judgment part 51c Warm-up completion judgment threshold value setting part 51d Integrated electric power generation amount calculation part 52 Temperature sensor (temperature detection means)
53 Current sensor 54 Voltage sensor

Claims (2)

A fuel cell that is supplied with oxidant gas and fuel gas to generate power;
A radiator that dissipates the refrigerant warmed by the fuel cell;
A refrigerant circulation pump for circulating refrigerant between the fuel cell and the radiator;
An oxidant gas supply means for supplying an oxidant gas to the cathode of the fuel cell;
A back pressure valve for adjusting the pressure of the cathode of the fuel cell;
Temperature detecting means for detecting the temperature of the fuel cell;
A warm-up promotion control unit that controls the fuel cell to warm up;
A warm-up completion determination unit for determining completion of warm-up of the fuel cell,
In the fuel cell system that performs the warm-up promotion control by the warm-up promotion control unit until it is determined by the warm-up completion determination unit that the warm-up is completed,
Based on the temperature at the time of start-up of the fuel cell detected by the temperature detecting means, a warm-up completion determination threshold value is set so that the warm-up completion determination is delayed as the temperature of the fuel cell at the time of start-up is lower further have a complete determination threshold setting unit,
The warm-up promotion control unit controls the refrigerant circulation pump to reduce the flow rate of the refrigerant supplied to the fuel cell, and controls the oxidant gas supply means, compared to a case where warm-up is not promoted. Performing at least one of increasing the flow rate of an oxidant gas supplied to the cathode of the fuel cell, and increasing the pressure of the cathode of the fuel cell by controlling the back pressure valve;
When the temperature of the fuel cell detected by the temperature detection means reaches a predetermined temperature that is the warm-up completion determination threshold set by the warm-up completion determination threshold setting unit, the warm-up completion determination unit warms up the fuel cell. It is determined that the fuel cell system is completed . A fuel cell that is supplied with oxidant gas and fuel gas to generate power;
A radiator that dissipates the refrigerant warmed by the fuel cell;
A refrigerant circulation pump for circulating refrigerant between the fuel cell and the radiator;
An oxidant gas supply means for supplying an oxidant gas to the cathode of the fuel cell;
A back pressure valve for adjusting the pressure of the cathode of the fuel cell;
Temperature detecting means for detecting the temperature of the fuel cell;
A warm-up promotion control unit that controls the fuel cell to warm up;
A warm-up completion determination unit that determines completion of warm-up of the fuel cell,
In the fuel cell system that performs warm-up promotion control by the warm-up promotion control unit until the warm-up completion determination unit determines warm-up completion,
A warm-up completion determination threshold setting unit configured to set a warm-up completion determination threshold based on the temperature at the time of startup of the fuel cell detected by the temperature detection unit;
The warm-up completion determination threshold value setting unit sets the warm-up completion determination threshold value higher as the temperature of the fuel cell at startup is lower ,
The warm-up promotion control unit controls the refrigerant circulation pump to reduce the flow rate of the refrigerant supplied to the fuel cell, and controls the oxidant gas supply means, compared to a case where warm-up is not promoted. Performing at least one of increasing the flow rate of an oxidant gas supplied to the cathode of the fuel cell, and increasing the pressure of the cathode of the fuel cell by controlling the back pressure valve;
When the temperature of the fuel cell detected by the temperature detection means reaches a predetermined temperature that is the warm-up completion determination threshold set by the warm-up completion determination threshold setting unit, the warm-up completion determination unit warms up the fuel cell. It is determined that the fuel cell system is completed .

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