US20020064697A1 - Fuel cell output characteristic estimation apparatus and output characteristic estimation method, fuel cell system and vehicle having the same, and fuel cell output control method and data storage medium - Google Patents

Fuel cell output characteristic estimation apparatus and output characteristic estimation method, fuel cell system and vehicle having the same, and fuel cell output control method and data storage medium Download PDF

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US20020064697A1
US20020064697A1 US09/990,264 US99026401A US2002064697A1 US 20020064697 A1 US20020064697 A1 US 20020064697A1 US 99026401 A US99026401 A US 99026401A US 2002064697 A1 US2002064697 A1 US 2002064697A1
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Prior art keywords
fuel cell
output
output characteristic
terminals
voltage
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Abandoned
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US09/990,264
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English (en)
Inventor
Hiroshi Sugiura
Nobuo Watanabe
Kouta Manabe
Tetsuhiro Ishikawa
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Toyota Motor Corp
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Toyota Motor Corp
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Publication of US20020064697A1 publication Critical patent/US20020064697A1/en
Priority to US10/852,178 priority Critical patent/US7410711B2/en
Assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA reassignment TOYOTA JIDOSHA KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ISHIKAWA, TETSUHIRO, MANABE, KOUTA, SUGIURA, HIROSHI, WATANABE, NOBUO
Priority to US12/140,737 priority patent/US20080254329A1/en
Priority to US12/690,417 priority patent/US8518590B2/en
Abandoned legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/30—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling fuel cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02T90/40—Application of hydrogen technology to transportation, e.g. using fuel cells

Definitions

  • the invention relates to a fuel cell output characteristic estimation apparatus and an output characteristic estimation method, a fuel cell system and a vehicle having the same, and a fuel cell output control method and a data storage medium that stores a program to implement the method. More particularly, the invention relates to an output characteristic estimation apparatus that estimates an output characteristic of a fuel cell and an output characteristic estimation method for estimating an output characteristic of a fuel cell, a fuel cell system having a fuel cell and a vehicle having the fuel cell system, and a fuel cell output control method for controlling an output of the fuel cell and a data storage medium that stores a computer-readable program that causes a computer to function as a fuel cell output characteristic arithmetic unit and/or a control unit for the fuel cell system.
  • the applicant of the invention has proposed a system that determines a fuel cell output by taking account of the output characteristic of the fuel cell for the purpose of enhancing an energy efficiency of the fuel cell system (see JP-A-2000-12059).
  • a fuel cell output characteristic estimating apparatus for estimating an output characteristic of a fuel cell includes a current-voltage detector that detects an output current of the fuel cell and a voltage between terminals of the fuel cell, and a controller that estimates the output characteristic of the fuel cell on the basis of the detected output current and the detected voltage between the terminals, detected by the current-voltage detector, and a basic output characteristic of the fuel cell.
  • the aforementioned fuel cell output characteristic estimation apparatus allows accurate estimation of an output characteristic at a specific timing of a fuel cell that has been used over an extended period of time on the basis of the detected output current, the detected voltage between terminals, and the basic output characteristic of the fuel cell.
  • the output characteristic of the fuel cell represents a relationship between the output current of the fuel cell and the output voltage of the fuel cell.
  • the controller derives the basic output characteristic from at least one of a fuel supply pressure applied to the fuel cell and a temperature of the fuel cell.
  • the controller derives the basic output characteristic from an output characteristic of the fuel cell corresponding to at least one of the fuel supply pressure applied to the fuel cell and the temperature of the fuel cell, and an internal resistance of the fuel cell corresponding to the temperature of the fuel cell.
  • the controller estimates an internal resistance of the fuel cell on the basis of the detected output current and the detected voltage between the terminals, and the basic output characteristic, and estimates the output characteristic of the fuel cell on the basis of the estimated internal resistance of the fuel cell. This may allow more appropriate estimation of the output characteristic of the fuel.
  • the controller estimates the output characteristic of the fuel cell on the basis of the output characteristic corresponding to at least one of the fuel supply pressure applied to the fuel cell and the temperature of the fuel cell, and the estimated internal resistance.
  • a fuel cell system having a fuel cell includes a fuel cell output characteristic estimating apparatus for estimating an output characteristic of the fuel cell, including a current-voltage detector that detects an output current of the fuel cell and a voltage between terminals of the fuel cell, and a controller that estimates the output characteristic of the fuel cell on the basis of the detected output current and the detected voltage between the terminals, detected by the current-voltage detector, and a basic output characteristic of the fuel cell; sets a target output of the fuel cell using the output characteristic of the fuel cell estimated by the controller; and adjusts an output of the fuel cell such that the set target output is generated by the fuel cell.
  • the aforementioned fuel cell system controls the output of the fuel cell using a more optimized fuel cell output characteristic, resulting in an efficient operation of the fuel cell. Accordingly an energy efficiency of the entire system can be enhanced.
  • the aforementioned fuel cell system includes a power supply that supplies electric power to and receives the electric power from the fuel cell system, in which the controller sets the target output of the fuel cell on the basis of an output required to be generated by the fuel cell system.
  • the controller is operable to control (i.e., change) supply of the electric power to or from the power supply.
  • control i.e., change
  • the controller includes a transformer that is connected to terminals of the power supply and transforms the voltage between the terminals of the power supply so as to be applied to output terminals of the fuel cell.
  • the controller changes the voltage between the terminals of the fuel cell into a voltage corresponding to the set target output.
  • the use of a more optimized output characteristic of the fuel cell allows the fuel cell to generate a required output by controlling a voltage between terminals of the fuel cell into a voltage corresponding to the required output.
  • a vehicle includes a fuel cell system having a fuel cell output characteristic estimating apparatus for estimating an output characteristic of the fuel cell, including a current-voltage detector that detects an output current of the fuel cell and a voltage between terminals of the fuel cell, and a controller that estimates the output characteristic of the fuel cell on the basis of the detected output current and the detected voltage between the terminals, detected by the current-voltage detector, and a basic output characteristic of the fuel cell.
  • the controller sets a target output of the fuel cell using the output characteristic of the fuel cell estimated by the controller, and adjusts an output of the fuel cell such that the set target output is generated by the fuel cell. Since the fuel cell system uses a more optimized output characteristic of the fuel cell to adjust the output from the fuel cell for the efficient operation of the fuel cell, the vehicle having this type of the fuel cell system may achieve a high energy efficiency.
  • a method of estimating an output characteristic of a fuel cell includes the steps of (a) estimating a basic output characteristic of the fuel cell on the basis of at least one of a fuel supply pressure applied to the fuel cell and a temperature of the fuel cell; and (b) estimating the output characteristic of the fuel cell on the basis of the estimated basic output characteristic of the fuel cell, a detected output current of the fuel cell, and a detected voltage between terminals of the fuel cell.
  • the basic output characteristic of the fuel cell is estimated using an output characteristic corresponding to at least one of the fuel supply pressure applied to the fuel cell and the temperature of the fuel cell, and an internal resistance of the fuel cell corresponding to the temperature of the fuel cell. This allows the fuel cell output characteristic to be estimated even more appropriately.
  • the output characteristic of the fuel cell is estimated using an internal resistance of the fuel cell estimated on the basis of the detected output current, the detected voltage between the terminals of the fuel cell, and the basic output characteristic. This allows the fuel cell output characteristic to be estimated more appropriately.
  • the output characteristic of the fuel cell is estimated using an output characteristic corresponding to at least one of the fuel supply pressure applied to the fuel cell and the temperature of the fuel cell, and the estimated internal resistance of the fuel cell.
  • a method of controlling an output of a fuel cell includes the steps of (a) setting a target output using an estimated output characteristic of the fuel cell, wherein the output characteristic of the fuel cell is estimated by the steps of (i) estimating a basic output characteristic of the fuel cell on the basis of at least one of a fuel supply pressure applied to the fuel cell and a temperature of the fuel cell, and (ii) estimating the output characteristic of the fuel cell on the basis of the estimated basic output characteristic of the fuel cell, a detected output current of the fuel cell, and a detected voltage between terminals of the fuel cell; and (b) controlling an output of the fuel cell such that the fuel cell generates the set target output.
  • a target output is set on the basis of an output required to be generated by a fuel cell system including a power supply that supplies electric power to and receives the electric power from the fuel cell system, and when the set target output of the fuel cell is in excess of or short of the required output of the fuel cell system, supply of the electric power to or from the power supply is changed.
  • a voltage between the terminals of the power supply connected to output terminals of the fuel cell is transformed such that the voltage between the terminals of the fuel cell becomes a voltage corresponding to the target output.
  • the aforementioned data storage medium allows a computer to serve as a fuel cell output characteristic arithmetic unit that is capable of computing the output characteristic at a specific timing of a fuel cell which has been used for an extended period of time, on the basis of the detected output current, the detected voltage between terminals of the fuel cell, and the fuel cell basic output characteristic.
  • the computing program derives the basic output characteristic using an output characteristic corresponding to at least one of the fuel supply pressure applied to the fuel cell and the temperature of the fuel cell, and an internal resistance of the fuel cell corresponding to the temperature of the fuel cell
  • the computing program estimates the output characteristic of the fuel cell using an internal resistance of the fuel cell estimated on the basis of the detected output current, the detected voltage between the terminals of the fuel cell, and the basic output characteristic.
  • the computing program derives the output characteristic of the fuel cell using an output characteristic corresponding to at least one of the fuel supply pressure applied to the fuel cell and the temperature of the fuel cell, and the estimated internal resistance.
  • a data storage medium that stores a computer readable program that causes a computer to function as a device for controlling a fuel cell includes a computing program that derives a basic output characteristic of the fuel cell on the basis of at least one of a fuel supply pressure applied to the fuel cell and a temperature of the fuel cell; derives the output characteristic of the fuel cell on the basis of the derived basic output characteristic of the fuel cell, a detected output current of the fuel cell, and a detected voltage between terminals of the fuel cell; sets a target output of the fuel cell using the derived output characteristic of the fuel cell; and controls the output of the fuel cell such that the fuel cell generates the set target output.
  • the aforementioned data storage medium allows the computer to serve as a control unit for the fuel cell system for controlling the output of the fuel cell using more optimized fuel cell output characteristic so as to operate the fuel cell efficiently.
  • the computing program sets the target output on the basis of the output required to be generated by the fuel cell system including the power supply that supplies electric power to and receives the electric power from the fuel cell, and to change the supply of the electric power to or from the power supply when the set target output of the fuel cell is in excess of or short of the required output of the fuel cell system.
  • the computing program can cause the transformation of the voltage between the terminals of the power supply connected to the output terminals of the fuel cell such that the voltage between terminals of the fuel cell becomes a voltage corresponding to the set target output.
  • FIG. 1 is a block diagram showing a schematic configuration of a fuel cell system mounted on a vehicle according to an embodiment of the invention
  • FIG. 2 is a flowchart showing a typical output characteristic estimation process routine explaining how the output characteristic of the fuel cell is estimated
  • FIG. 3 is a flowchart showing a typical output characteristic correction process routine executed by an electronic control unit for the fuel cell system according to an embodiment of the invention
  • FIG. 4 is a typical map showing a relationship between a fuel cell temperature Tfc and a basic internal resistance R 0 ;
  • FIG. 5 is a typical map showing a relationship between an output current Ifc and an output voltage Vfc of the fuel cell at varied hydrogen supply pressures Ph applied to the fuel cell with no internal resistance;.
  • FIG. 6 is an explanatory view showing a typical process of obtaining the output characteristic of the fuel cell from the basic output characteristic
  • FIG. 7 is an explanatory view showing a typical process of correcting the output characteristic of the fuel cell
  • FIG. 8 is a flowchart showing a typical output control routine executed by the electronic control unit for the fuel cell system according to an embodiment of the invention.
  • FIG. 9 is a typical map showing a relationship between the output current Ifc and the output voltage Vfc of the fuel cell at varied fuel cell temperatures Tfc of the fuel cell;
  • FIG. 10 is an explanatory view showing a typical process of correcting the output characteristic of the fuel cell when a fuel cell output Pfc is low.
  • FIGS. 11A through 11C are maps each showing a relationship between the output current Ifc and the output voltage Vfc of the fuel cell with no internal resistance at varied fuel cell temperatures Tfc and varied hydrogen supply pressures Ph applied to the fuel cell, respectively.
  • FIG. 1 is a block diagram showing a schematic configuration of a fuel cell system 20 installed in a vehicle according to one embodiment of the invention.
  • the fuel cell system 20 according to the embodiment is provided with a fuel cell 26 constructed, for example, as a polymer electrolyte fuel cell, that generates power using hydrogen supplied by a hydrogen tank 22 and oxygen contained in an air supplied by a blower 24 , a DC/DC converter 32 that regulates a voltage of a power line 28 connected to an output terminal of the fuel cell 26 and charges/discharges a battery 30 supplying power to an accessory 33 , an inverter 34 that is connected to the power line 28 , a motor 36 that is driven through switching of a switching device of an inverter 34 to provide a driving power from a driving shaft 38 , and an electronic control unit (ECU) 40 that controls the entire system.
  • the driving shaft 38 is connected through a reduction gear 12 to driving wheels 14 of a vehicle, and
  • the ECU 40 is a microprocessor including a CPU 42 , ROM 44 that stores processing programs, RAM 46 that temporarily stores data, and an I/O port (not shown).
  • Data input to the ECU 40 through the input port include a hydrogen supply pressure Ph detected by a pressure sensor 50 mounted to a supply pipe from the hydrogen tank 22 to the fuel cell 26 , a fuel cell temperature Tfc detected by a temperature sensor 52 mounted on the fuel cell 26 , an output voltage Vfc from the fuel cell 26 detected by a voltage sensor 54 mounted across output terminals of the fuel cell 26 , an output current Ifc of the fuel cell 26 detected by a current sensor 56 mounted on an output terminal of the fuel cell 26 , a current of each phase applied to the motor 26 detected by a current sensor (not shown) mounted in the inverter 34 , an angle of revolution of a rotor of the motor 36 detected by an angle sensor (not shown) mounted on the motor 36 , a vehicle speed V detected by a vehicle speed sensor 58 , a shift position SP detected by a
  • signals output from the ECU 40 through the output port include a driving signal for the blower 24 , a control signal for the DC/DC converter 32 , a control signal for the inverter 34 , and a control signal for the reduction gear 12 .
  • FIG. 2 is a flowchart showing a typical output characteristic correction process routine executed by the ECU 40 for the fuel cell system 20 according to the embodiment.
  • the output characteristic estimation process routine shown in FIG. 2 is executed by the ECU 40 of the fuel cell system 20 not only when the output characteristic is estimated but also when the fuel cell temperature Tfc or the hydrogen supply pressure Ph changes.
  • step S 100 the CPU 42 of the ECU 40 reads the hydrogen supply pressure Ph detected by the pressure sensor 50 and the fuel cell temperature Tfc detected by the temperature sensor 52 . Then in step S 102 , a basic internal resistance R 0 of the fuel cell 26 and a theoretical output characteristic are derived.
  • the basic internal resistance R 0 is derived from a map stored in the ROM 44 , in which an experimentally obtained relationship between the fuel cell temperature Tfc and the basic internal resistance R 0 is preliminarily stored. When the fuel cell temperature Tfc is given, the basic internal resistance R 0 can be derived in relation with the given value of the fuel cell temperature Tfc in the map.
  • FIG. 4 shows an example of the map representing a relationship between the fuel cell temperature Tfc and the basic internal resistance R 0 .
  • a map representing a relationship between output current Ifc and output voltage Vfc of the fuel cell 26 with no internal resistance at each hydrogen supply pressure Ph is preliminarily stored in the ROM 44 .
  • the theoretical output characteristic is derived as the relationship between the output current Ifc and the output voltage Vfc from the map by referring to the given value of the hydrogen supply pressure Ph.
  • FIG. 5 is an example of the map showing the relationship between the output current Ifc and the output voltage Vfc of the fuel cell 26 at varied hydrogen supply pressures Ph applied to the fuel cell 26 .
  • step S 104 a basic output characteristic is computed using the derived basic internal resistance R 0 and the theoretical output characteristic.
  • the basic output characteristic is computed by incorporating the basic internal resistance R 0 into the theoretical output characteristic.
  • the basic output characteristic can be obtained by the following equation (1).
  • V1 V0 ⁇ R 0 ⁇ I (1)
  • V0 represents the output voltage of the theoretical output characteristic corresponding to an output current I
  • V1 represents the output voltage of the basic output characteristic corresponding to the output current I.
  • step S 106 specific points Vs 0 , Is 0 on the obtained basic output characteristic are set as operation points Vfc*, Ifc* of the fuel cell 26 .
  • step S 108 the DC/DC converter 32 is controlled such that the fuel cell 26 is operated at the operation points set in step S 106 . More specifically, the DC/DC converter 32 is controlled to adjust the voltage of the power line 28 to the voltage at the operation point Vfc*.
  • step S 110 the output voltage Vfc detected by the voltage sensor 54 and the output current Ifc detected by the current sensor 56 are read. Then in step S 112 , the output current Ifc read in step S 110 and the basic output characteristic obtained through computation in step S 104 are used to derive an output voltage Vfc 0 on the basic output characteristic corresponding to the output current Ifc.
  • step S 114 a deviation between the output voltage Vfc 0 on the basic output characteristic and the output voltage Vfc detected by the voltage sensor 54 is divided by the output current Ifc to obtain the internal resistance deviation ⁇ R.
  • step S 116 the internal resistance deviation ⁇ R is added to the basic internal resistance R 0 to obtain an internal resistance R 1 of the fuel cell 26 .
  • step S 118 the output characteristic of the fuel cell 26 is derived from the following equation (2) using the internal resistance R 1 calculated in step S 116 .
  • V2 is the output voltage of the output characteristic of the fuel cell 26 corresponding to the output current I.
  • FIG. 6 shows a typical process of obtaining the output characteristic of the fuel cell 26 from the basic output characteristic.
  • V2 V0 ⁇ R 1 ⁇ I (2)
  • the output characteristic estimation process routine as exemplified in the flowchart of FIG. 2 is executed.
  • an output characteristic correction process routine as exemplified in the flowchart of FIG. 3, is repeatedly executed to correct the output characteristic of the fuel cell 26 .
  • the aforementioned correction routine corresponds basically to the control scheme from step S 110 to S 118 of the flowchart as shown in FIG. 2.
  • the output characteristic correction process is different from the control scheme of the output characteristic estimating routine in that the previous output characteristic is used (S 202 in FIG. 3) instead of using the basic output characteristic (S 112 in FIG. 2) and the internal resistance R 1 is derived from a proportional term and an integral term (S 206 in FIG. 3).
  • step S 202 the output current Ifc read in step S 200 and the output characteristic of the fuel cell 26 obtained through computation executed in the previous cycle are used to derive an output voltage Vfc 1 on the output characteristic corresponding to the output current Ifc. Then in step S 204 , a deviation between the output voltage Vfc 1 on the output characteristic and the output voltage Vfc is divided by the output current Ifc to obtain the internal resistance deviation ⁇ R. In step S 206 , the internal resistance R 1 of the fuel cell 26 is computed using the following equation (3).
  • R 1 R 0 + Kp ⁇ R+Ki ⁇ Rdt (3)
  • Kp is a gain in the proportional term and Ki is a gain in the integral term.
  • step S 208 the output characteristic of the fuel cell 26 is derived from the equation (2) using the internal resistance R 1 , and the process returns.
  • FIG. 7 shows an example of correction of the output characteristic of the fuel cell 26 .
  • the output characteristic estimation process and the output characteristic correction process executed by the ECU 40 may provide more accurate output characteristic of the fuel cell 26 that has been used over an extended period of time.
  • FIG. 8 is a flowchart showing a typical output control routine executed by the ECU 40 for the fuel cell system 20 according to the embodiment. This routine is executed repeatedly at a predetermined time interval (for example, at every 8 msec.).
  • step S 300 the CPU 42 of the ECU 40 reads various data including a vehicle speed V detected by the vehicle speed sensor 58 , an accelerator pedal position AP detected by the accelerator pedal position sensor 63 , and a brake pedal position BP detected by the brake pedal position sensor 65 . Then in step S 302 , a value of an output to be supplied to the driving shaft 38 , namely, output requirement P 0 for the system is computed on the basis of the data including the accelerator pedal position AP, the brake pedal position BP, and the vehicle speed V that have been read in step S 300 .
  • a map containing the relationship between the output requirement P 0 and the data including the accelerator pedal position AP, the brake pedal position BP, and the vehicle speed V is stored in the ROM 44 .
  • the output requirement P 0 can be derived from the map in accordance with a given value of the data including the accelerator pedal position AP, brake pedal position BP, and the vehicle speed V in relation with the output requirement P 0 .
  • step S 304 the output requirement P 0 is distributed to a fuel cell output Pfc generated by the fuel cell 26 and a battery output Pb generated by a battery 30 . More specifically, the fuel cell output Pfc is set to allow efficient operation of the fuel cell 26 within its output range using the output characteristic estimated by the output characteristic estimating process routine shown in FIG. 2 or corrected by the output characteristic correcting process routine shown in FIG. 3. Then the battery output Pb is set to cover the short or excessive supply of the output of the Pfc.
  • step S 306 the operation points Vfc*, Ifc* of the fuel cell 26 are set on the basis of the fuel cell output Pfc. Then in step S 308 , the DC/DC converter 32 is controlled such that the voltage of the power line 28 reaches the operation point voltage Vfc*.
  • step S 310 the inverter 34 is controlled such that the output requirement P 0 is supplied from the motor 36 to the driving shaft 38 , and the process returns. Since the inverter 34 is controlled in accordance with a general process, the detailed description of such control, thus, is omitted.
  • the fuel cell output Pfc is distributed on the basis of a more accurate output characteristic of the fuel cell 26 . Accordingly, the fuel cell 26 can be efficiently operated, improving energy efficiency of the entire system. Moreover, a short or an excessive supply of the fuel cell output Pfc is covered by the output Pb generated by the battery 30 such that the output requirement P 0 is supplied to the driving shaft 38 .
  • the theoretical output characteristic is derived from the hydrogen supply pressure Ph. It is also possible to derive the theoretical output characteristic from the fuel cell temperature Tfc.
  • a map containing the output current Ifc and the output voltage Vfc of the fuel cell 26 with no internal resistance at varied temperatures Tfc of the fuel cell 26 is stored in the ROM 44 . Then a theoretical output characteristic representing the relationship between the output current Ifc and the output voltage Vfc is derived from a given value of the fuel cell temperature Tfc.
  • FIG. 9 is an example of the map showing a relationship between the output current Ifc and the output voltage Vfc of the fuel cell 26 having no internal resistance at varied fuel cell temperatures Tfc.
  • the theoretical output characteristic may be derived from the fuel cell temperature Tfc because an accurate theoretical output characteristic can be obtained by using the fuel cell temperature Tfc even in the low output range with reduced error (range at a high output voltage and low output current).
  • FIG. 10 shows an output characteristic estimated on the basis of a theoretical output characteristic derived from the hydrogen supply pressure Ph (dashed line indicated as previous output characteristic), and output characteristic (dashed line indicated as corrected output characteristic) obtained through the routine shown in FIG. 2 or FIG. 3 on the basis of the output voltage Vfc detected by the voltage sensor 54 and the output current Ifc detected by the current sensor 56 (at a measurement point shown in FIG. 10) during operation of the fuel cell 26 in the low output range (at a set point shown in FIG.
  • the corrected output characteristic line deviates from the line representing a true output characteristic shown by a solid line in FIG. 10.
  • the theoretical output characteristic with high accuracy can be derived from the fuel cell temperature Tfc even in the low output range. Accordingly, even when the fuel cell 26 is operated in the low output range, the resultant output characteristic may become closer to the true output characteristic.
  • an input of the hydrogen supply pressure Ph is not necessary in step S 100 of the routine shown in FIG. 2.
  • the theoretical output characteristic is derived from the fuel cell temperature Tfc. It is also possible to derive the theoretical output characteristic using the hydrogen supply pressure Ph and the fuel cell temperature Tfc. In this case, instead of deriving the theoretical output characteristic executed in step S 102 of FIG. 2, a map containing a relationship between the output current Ifc and the output voltage Vfc of the fuel cell 26 with no internal resistance at varied fuel cell temperatures Tfc and varied hydrogen supply pressures Ph is stored in the ROM 44 . Then the theoretical output characteristic represented by the relationship between the output current Ifc and the output voltage Vfc in the map can be derived from given values of the fuel cell temperature Tfc and the hydrogen supply pressure Ph.
  • FIGS. 11A to 11 C show examples of maps representing a relationship between the output current Ifc and the output voltage Vcf of the fuel cell 26 with no internal resistance at the respective fuel cell temperatures Tfc and the respective hydrogen supply pressures Ph.
  • the basic internal resistance R 0 is derived from the fuel cell temperature Tfc and, at the same time, the theoretical output characteristic taking into account no internal resistance is derived from the hydrogen supply pressure Ph in the fuel cell system 20 .
  • the theoretical output characteristic is derived from the hydrogen supply pressure Ph taking into account a predetermined internal resistance.
  • the basic internal resistance R 0 is derived from the fuel cell temperature Tfc and, at the same time, the theoretical output characteristic taking into account no internal resistance is derived from the fuel cell temperature Tfc.
  • the basic internal resistance R 0 is derived from the fuel cell temperature Tfc and, at the same time, the theoretical output characteristic taking into account no internal resistance is derived from the fuel cell temperature Tfc and the hydrogen supply pressure Ph.
  • the theoretical output characteristic taking into account a predetermined internal resistance from the fuel cell temperature Tfc it is possible to derive the theoretical output characteristic taking into account a predetermined internal resistance from the fuel cell temperature Tfc and to derive the theoretical output characteristic taking into account a predetermined internal resistance from the hydrogen supply pressure Ph and the fuel cell temperature Tfc.
  • the output characteristic estimation process routine shown in FIG. 2 is executed when the fuel cell temperature Tfc or the hydrogen supply pressure Ph changes and the output characteristic correction process routine shown in FIG. 3 is repeatedly executed thereafter. It is again possible to repeatedly execute the output characteristic estimation process routine shown in FIG. 2 irrespective of the change in the fuel cell temperature Tfc or the hydrogen supply pressure Ph. In this case, execution of the output characteristic correction process routine shown in FIG. 3 may or may not be executed.
  • the fuel cell system 20 is structured so as to be installed in a vehicle. It is possible that the fuel cell system 20 is employed in a ship, aircraft, or other movable object other than the vehicle, or a freestanding power drive apparatus.
  • the fuel cell system 20 estimates or corrects output characteristic of the fuel cell 26 as a source of driving the motor 36 . It is possible to apply the embodiment to a system that estimates or corrects output characteristic of a fuel cell functioning as a power source for supplying power to a general load that consumes electric power. In addition, it is preferable that the embodiment be applied to a computer-readable data storage medium that stores a program that causes a computer to serve as an output characteristic estimating apparatus or an output characteristic correction apparatus that performs output characteristic estimation processes or output characteristic correction processes for the fuel cell.
  • the recording medium can be, for example, CD-ROMs and flexible disks. The recording medium can be readily removable, as are the previously noted examples, or fixed, such as with a hard drive or a computer chip. Use of such a data storage medium permits the same effects as those derived from the invention to be obtained by installing a program according to the embodiment of the invention in a fuel cell system.
  • the controller (ECU 40 ) is implemented as a programmed general purpose computer. It will be appreciated by those skilled in the art that the controller can be implemented using a single special purpose integrated circuit (e.g., ASIC) having a main or central processor section for overall, system-level control, and separate sections dedicated to performing various different specific computations, functions and other processes under control of the central processor section.
  • the controller can be a plurality of separate dedicated or programmable integrated or other electronic circuits or devices (e.g., hardwired electronic or logic circuits such as discrete element circuits, or programmable logic devices such as PLDs, PLAs, PALs or the like).
  • the controller can be implemented using a suitably programmed general purpose computer, e.g., a microprocessor, microcontroller or other processor device (CPU or MPU), either alone or in conjunction with one or more peripheral (e.g., integrated circuit) data and signal processing devices.
  • a suitably programmed general purpose computer e.g., a microprocessor, microcontroller or other processor device (CPU or MPU)
  • CPU or MPU processor device
  • peripheral e.g., integrated circuit
  • a distributed processing architecture can be used for maximum data/signal processing capability and speed.
US09/990,264 2000-11-28 2001-11-23 Fuel cell output characteristic estimation apparatus and output characteristic estimation method, fuel cell system and vehicle having the same, and fuel cell output control method and data storage medium Abandoned US20020064697A1 (en)

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Application Number Priority Date Filing Date Title
US10/852,178 US7410711B2 (en) 2000-11-28 2004-05-25 Fuel cell output characteristic estimation apparatus and output characteristic estimation method, fuel cell system and vehicle having the same, and fuel cell output control method and data storage medium
US12/140,737 US20080254329A1 (en) 2000-11-28 2008-06-17 Fuel cell output characteristic estimation apparatus and output characteristic estimation method, fuel cell system and vehicle having the same, and fuel cell output control method and data storage medium
US12/690,417 US8518590B2 (en) 2000-11-28 2010-01-20 Fuel cell output characteristic estimation apparatus and output characteristic estimation method, fuel cell system and vehicle having the same, and fuel cell output control method and data storage medium

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JP2000361076 2000-11-28
JP2000-361076 2000-11-28
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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020153180A1 (en) * 2001-02-22 2002-10-24 Toyota Jidosha Kabushiki Kaisha Accessory drive apparatus
US20040065489A1 (en) * 2002-05-24 2004-04-08 Ballard Power Systems Ag Method and apparatus to regulate the supply of power to an electric drive using a hybrid energy supply system in a vehicle
US20040083039A1 (en) * 2002-10-23 2004-04-29 Ford Motor Company Method and system for controlling power distribution in a hybrid fuel cell vehicle
US6847127B1 (en) * 2002-06-28 2005-01-25 Hyundai Motor Company System and method for controlling power distribution of fuel cell hybrid electric vehicle
US20050244688A1 (en) * 2002-12-25 2005-11-03 Nissan Motor Co., Ltd. Power generation control system for fuel cell
US20050277006A1 (en) * 2004-06-15 2005-12-15 Webasto Ag Fuel cell system
US20090011301A1 (en) * 2006-01-31 2009-01-08 Nissan Motor Co., Ltd. Controlling the Requested Power Output of a Fuel Cell System
US20090061263A1 (en) * 2006-01-30 2009-03-05 Toyota Jidosha Kabushiki Kaisha Fuel cell system and method for estimating output characteristic of fuel cell
US20090278405A1 (en) * 2008-05-08 2009-11-12 Gm Global Technology Operations, Inc. Systems and methods for multiple source power conversion
US20100025133A1 (en) * 2007-02-14 2010-02-04 Kenichi Hamada Power supply system
US20140272651A1 (en) * 2007-04-26 2014-09-18 Toyota Jidosha Kabushiki Kaisha Fuel cell system
US20160244008A1 (en) * 2013-09-23 2016-08-25 Powidian Method and system for managing energy on board a vehicle
US10005364B1 (en) * 2015-12-08 2018-06-26 Roberto Laboy Vehicle alternative power system

Families Citing this family (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10233821A1 (de) * 2002-07-25 2004-02-05 Daimlerchrysler Ag Verfahren und Anordnung zur Steuerung der Energieversorgung einer wenigstens einen elektrischen Antriebsmotor aufweisenden, mobilen Vorrichtung mit einem hybriden Energiesystem, das ein Brennstoffzellensystem und ein dynamisches Energiesystem enthält
JP4352688B2 (ja) 2002-11-27 2009-10-28 トヨタ自動車株式会社 燃料電池の診断装置および診断方法
JP4506075B2 (ja) * 2002-11-27 2010-07-21 トヨタ自動車株式会社 燃料電池の診断装置
JP4501060B2 (ja) * 2004-03-08 2010-07-14 トヨタ自動車株式会社 燃料電池電源装置
US20050287402A1 (en) * 2004-06-23 2005-12-29 Maly Douglas K AC impedance monitoring of fuel cell stack
JP4784076B2 (ja) * 2004-11-26 2011-09-28 日産自動車株式会社 燃料電池システムの制御装置
JP5023432B2 (ja) * 2005-03-23 2012-09-12 日産自動車株式会社 燃料電池システムの制御装置及び燃料電池システムの制御方法
JP4940569B2 (ja) * 2005-04-06 2012-05-30 日産自動車株式会社 燃料電池システム
JP4924790B2 (ja) * 2005-06-30 2012-04-25 トヨタ自動車株式会社 燃料電池システム
JP5146898B2 (ja) * 2005-08-10 2013-02-20 トヨタ自動車株式会社 燃料電池電源制御装置、燃料電池システム及び燃料電池電源制御方法
US20100266875A1 (en) * 2006-11-13 2010-10-21 Ryan Somogye Fuel Cell Power Management Module
ES2352709B1 (es) * 2007-04-26 2011-12-19 Universidad De Vigo Sistema modular de generación eléctrica basado en pilas de combustible.
JP4337104B2 (ja) * 2007-12-19 2009-09-30 トヨタ自動車株式会社 燃料電池システム
US8304929B2 (en) * 2009-06-18 2012-11-06 Lear Corporation Inverter with network interface
CN102511100B (zh) * 2009-09-25 2014-08-06 丰田自动车株式会社 燃料电池系统
JP5571434B2 (ja) * 2010-03-30 2014-08-13 大阪瓦斯株式会社 固体酸化物形燃料電池
JP5427832B2 (ja) * 2011-05-18 2014-02-26 本田技研工業株式会社 燃料電池車両
JP5345662B2 (ja) 2011-09-21 2013-11-20 本田技研工業株式会社 燃料電池システム
US9141923B2 (en) 2012-09-25 2015-09-22 Bloom Energy Corporation Optimizing contractual management of the total output of a fleet of fuel cells
KR102417895B1 (ko) * 2017-06-21 2022-07-07 현대자동차주식회사 연료전지 수명 예측 장치 및 방법, 그리고 차량 시스템
US10777831B2 (en) 2017-11-28 2020-09-15 Toyota Motor Engineering & Manufacturing North America, Inc. Equation based cooling system control strategy/method
US10720655B2 (en) 2017-11-28 2020-07-21 Toyota Motor Engineering & Manufacturing North America, Inc. Partial derivative based feedback controls for pid
US10714773B2 (en) 2017-11-28 2020-07-14 Toyota Motor Engineering & Manufacturing North America, Inc. Cooling system dT/dt based control
US11094950B2 (en) 2017-11-28 2021-08-17 Toyota Motor Engineering & Manufacturing North America, Inc. Equation based state estimator for cooling system controller
CN109606137B (zh) * 2019-01-23 2020-06-02 吉林大学 融合成本寿命因素的多源电驱动系统经济性优化方法
US10916788B2 (en) 2019-01-31 2021-02-09 Toyota Jidosha Kabushiki Kaisha Hydrogen supply system low pressure state estimator

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4839246A (en) * 1987-05-20 1989-06-13 Fuji Electric Co., Ltd. Generator system utilizing a fuel cell
US5290641A (en) * 1989-10-06 1994-03-01 Fuji Electric Co., Ltd. Method of controlling operation of fuel cell power supply

Family Cites Families (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1359673A (en) * 1971-06-09 1974-07-10 Procter & Gamble Ltd Quaternary ammonium compounds and surface treating compositions
JPS60107270A (ja) * 1983-11-14 1985-06-12 Shin Kobe Electric Mach Co Ltd 燃料電池多変数運転制御方法
JP2520963B2 (ja) 1989-08-24 1996-07-31 日本電信電話株式会社 燃料電池直流並列運転システム
JPH0458463A (ja) * 1990-06-25 1992-02-25 Fuji Electric Co Ltd 燃料電池発電システムの出力制御装置
DE4024454A1 (de) * 1990-08-01 1992-02-06 Reetz Manfred Prof Dr Verfahren zur anionischen polymerisation von (meth)acrylsaeurederivaten und (meth)acrylnitrilen und deren derivaten
JPH07105964A (ja) * 1993-10-05 1995-04-21 Fuji Electric Co Ltd 燃料電池発電装置およびその制御方法
JPH07123609A (ja) * 1993-10-22 1995-05-12 Fuji Electric Co Ltd 燃料電池給電システム
JP3567509B2 (ja) * 1994-11-10 2004-09-22 トヨタ自動車株式会社 燃料電池の駆動装置および触媒被毒率検出装置並びに燃料電池システム
KR0171207B1 (ko) * 1994-11-11 1999-03-30 와다 아키히로 고분자 전해질형 연료 전지와 그 운전 제어 방법
JP3428869B2 (ja) * 1997-08-26 2003-07-22 日本電信電話株式会社 燃料電池出力変動補償方法
JPH11195423A (ja) * 1997-08-29 1999-07-21 Nippon Telegr & Teleph Corp <Ntt> 燃料電池発電装置及び燃料電池劣化診断方法
JP4464474B2 (ja) 1998-06-25 2010-05-19 トヨタ自動車株式会社 燃料電池システム、燃料電池車両及び燃料電池制御方法
US6638652B1 (en) * 1998-10-02 2003-10-28 Toyota Jidosha Kabushiki Kaisha Fuel cell control apparatus
US6519539B1 (en) 2000-09-29 2003-02-11 Hydrogenics Corporation Measurement of fuel cell impedance
US20030054287A1 (en) * 2001-04-13 2003-03-20 Fuji Photo Film Co., Ltd. Resist composition

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4839246A (en) * 1987-05-20 1989-06-13 Fuji Electric Co., Ltd. Generator system utilizing a fuel cell
US5290641A (en) * 1989-10-06 1994-03-01 Fuji Electric Co., Ltd. Method of controlling operation of fuel cell power supply

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6942048B2 (en) * 2001-02-22 2005-09-13 Toyota Jidosha Kabushiki Kaisha Accessory drive apparatus
US20020153180A1 (en) * 2001-02-22 2002-10-24 Toyota Jidosha Kabushiki Kaisha Accessory drive apparatus
US20040065489A1 (en) * 2002-05-24 2004-04-08 Ballard Power Systems Ag Method and apparatus to regulate the supply of power to an electric drive using a hybrid energy supply system in a vehicle
US6953100B2 (en) * 2002-05-24 2005-10-11 Ballard Power Systems Ag Method and apparatus to regulate the supply of power to an electric drive using a hybrid energy supply system in a vehicle
US6847127B1 (en) * 2002-06-28 2005-01-25 Hyundai Motor Company System and method for controlling power distribution of fuel cell hybrid electric vehicle
US20040083039A1 (en) * 2002-10-23 2004-04-29 Ford Motor Company Method and system for controlling power distribution in a hybrid fuel cell vehicle
US6792341B2 (en) 2002-10-23 2004-09-14 Ford Motor Company Method and system for controlling power distribution in a hybrid fuel cell vehicle
US7700209B2 (en) 2002-12-25 2010-04-20 Nissan Motor Co., Ltd. Power generation control system for fuel cell
US20050244688A1 (en) * 2002-12-25 2005-11-03 Nissan Motor Co., Ltd. Power generation control system for fuel cell
US20050277006A1 (en) * 2004-06-15 2005-12-15 Webasto Ag Fuel cell system
US7172828B2 (en) * 2004-06-15 2007-02-06 Jeremy Carl Lawrence Fuel cell system
US20090061263A1 (en) * 2006-01-30 2009-03-05 Toyota Jidosha Kabushiki Kaisha Fuel cell system and method for estimating output characteristic of fuel cell
US20090011301A1 (en) * 2006-01-31 2009-01-08 Nissan Motor Co., Ltd. Controlling the Requested Power Output of a Fuel Cell System
US20100025133A1 (en) * 2007-02-14 2010-02-04 Kenichi Hamada Power supply system
US20140272651A1 (en) * 2007-04-26 2014-09-18 Toyota Jidosha Kabushiki Kaisha Fuel cell system
US20090278405A1 (en) * 2008-05-08 2009-11-12 Gm Global Technology Operations, Inc. Systems and methods for multiple source power conversion
US7936083B2 (en) * 2008-05-08 2011-05-03 GM Global Technology Operations LLC Systems and methods for multiple source power conversion
US20160244008A1 (en) * 2013-09-23 2016-08-25 Powidian Method and system for managing energy on board a vehicle
US9902287B2 (en) * 2013-09-23 2018-02-27 Powidian Method and system for managing energy on board a vehicle
US10005364B1 (en) * 2015-12-08 2018-06-26 Roberto Laboy Vehicle alternative power system

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