Fuel cell system and related control method

• US 20040076860A1
• Filed: 09/26/2003
• Published: 04/22/2004
• Est. Priority Date: 10/22/2002
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Aso, Takeshi
• Granted Patent: US 7,371,476 B2
• Time in Patent Office: Days
• US Class Current: 429/23
• CPC Class Codes: B60L 2210/10 DC to DC converters
• CPC Class Codes: B60L 58/31 for starting of fuel cells
• CPC Class Codes: B60L 58/33 by cooling
• CPC Class Codes: B60L 58/34 by heating
• CPC Class Codes: H01M 2008/1095 Fuel cells with polymeric electrolytes
• CPC Class Codes: H01M 2250/20 Fuel cells in motive systems, e.g. vehicle, ship, plane
• CPC Class Codes: H01M 8/04007 related to heat exchange
• CPC Class Codes: H01M 8/04268 Heating of fuel cells during the start-up of the fuel cells
• CPC Class Codes: H01M 8/04298 Processes for controlling fuel cells or fuel cell systems
• CPC Class Codes: H01M 8/04328 of anode reactants at the inlet or inside the fuel cell
• CPC Class Codes: H01M 8/04358 of the coolant
• CPC Class Codes: H01M 8/04388 of anode reactants at the inlet or inside the fuel cell
• CPC Class Codes: H01M 8/04395 of cathode reactants at the inlet or inside the fuel cell
• CPC Class Codes: H01M 8/04559 of fuel cell stacks
• CPC Class Codes: H01M 8/04589 of fuel cell stacks
• CPC Class Codes: H01M 8/0494 of fuel cell stacks
• CPC Class Codes: H01M 8/04955 Shut-off or shut-down of fuel cells
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility
• CPC Class Codes: Y02T 90/40 Application of hydrogen technology to transportation, e.g. using fuel cells

Abstract

A fuel cell system and a related control method are disclosed wherein, during start-up of a fuel cell stack 1, a controller 21 operates a DC/DC converter 13 in a voltage control mode to allow an electric power to be supplied from a secondary battery 7 to a load 6 at an output voltage managed by the DC/DC converter. Under such a condition, an electric power level appearing when a voltage level of the electric power to be supplied from the secondary battery to the load lies at a value greater than an open voltage level of the fuel cell stack 1. Next, the DC/DC converter 13 is operative in an electric power control mode to allow the electric power to be supplied from the secondary battery to the load at a managed electric power output. Then, a level of the electric power to be supplied to the load is detected with the DC/DC converter 13, which permits the electric power to be supplied from the secondary battery to the load at an electric power level less than a resulting detected electric power level.

Claims

1. A fuel cell system comprising:

a fuel cell stack supplied with fuel gas and oxidant gas to generate an electric power which is supplied through a diode to a load installed on a fuel cell powered vehicle;

a secondary battery by which an electric power is charged and discharged;

an electric power converter connected to the fuel cell stack through the diode to convert an electric power level, charged in the secondary battery, and supplying a converted electric power to the load; and

a controller operative to control the electric power converter in a way to allow a voltage level of the electric power, to be supplied from the secondary battery to the load, to lie at a value equal to or greater than an open voltage level of the fuel cell stack during start-up of the fuel cell stack, and to control the electric power converter in a way to allow an electric power level supplied to the load through the electric power converter to be detected for permitting the electric power to be supplied to the load from the secondary battery at an electric power level less than a detected electric power level.

2. The fuel cell system according to claim 1, wherein the controller controls the electric power converter in a way wherein, if an output electric current of the fuel cell stack, appearing when the electric power level supplied from the secondary battery to the load is decreased, is greater than a given value, reduction in the electric power level is interrupted.

3. The fuel cell system according to claim 1, wherein the controller controls the electric power converter in a way wherein, if an output voltage of the fuel cell stack, appearing when the electric power level supplied from the secondary battery to the load is decreased, is less than a given value, reduction in the electric power level is interrupted.

4. The fuel cell system according to claim 1, wherein the controller controls the electric power converter in a way to allow the temperature of the fuel cell stack, appearing when the voltage level of the electric power supplied from the secondary battery to the load is selected to lie at a value equal to the open voltage level of the fuel cell stack or at a value greater than the open voltage level of the fuel cell stack, to be detected whereupon, if the detected temperature of the fuel cell stack is less than a given value, the electric power converter detects the electric power level supplied to the load to allow the secondary battery to supply the electric power to the load at an electric power level less than resulting detected electric power level.

5. The fuel cell system according to claim 1, wherein the controller controls the electric power converter in a way to allow the voltage level of the fuel cell stack, appearing when the voltage level of the electric power supplied from the secondary battery to the load is selected to lie at a value equal to the open voltage level of the fuel cell stack or at a value greater than the open voltage level of the fuel cell stack, to be detected whereupon a timing, at which the electric power level to be supplied to the load through the electric power converter, is controlled depending upon a rise-up condition of the detected voltage level of the fuel cell stack.

6. A fuel cell system comprising:

a fuel cell stack supplied with fuel gas and oxidant gas to generate an electric power which is supplied through a diode to a load installed on a fuel cell powered vehicle;

a secondary battery by which an electric power is charged and discharged;

electric power converter means connected to the fuel cell stack through the diode and converting an electric power level, charged in the secondary battery, to be supplied to the load; and

control means operative to control the electric power converter means in a way to allow a voltage level of the electric power, to be supplied from the secondary battery to the load, to lie at a value equal to or greater than an open voltage level of the fuel cell stack during start up of the fuel cell stack, and to control the electric power converter means in a way to allow an electric power level supplied to the load through the electric power converter to be detected for permitting the electric power to be supplied to the load from the secondary battery at an electric power level less than a detected electric power level.

7. A method of controlling a fuel cell system, which has a fuel cell stack supplied with fuel gas and oxidant gas to generate an electric power which is supplied through a diode to a load installed on a fuel cell powered vehicle, and a secondary battery by which an electric power is charged and discharged, the method comprising:

converting a level of an electric power of the secondary battery to supply the electric power from the secondary battery to the load at a converted electric power level;

controlling such that, when starting up the fuel cell stack, a voltage level of the electric power to be supplied from the secondary battery to the load lies at a value equal to or greater than an open voltage level of the fuel cell stack; and

controlling such that the level of the electric power supplied to the load is detected to permit the electric power to be supplied to the load from the secondary battery at an electric power level less than a detected electric power level.