Fuel cell system and its control method

Patent metadata

Field	Value
Publication number	US-11817603-B2
Application number	US-201917762567-A
Country	US
Kind code	B2
Filing date	Sep 24, 2019
Priority date	Sep 24, 2019
Publication date	Nov 14, 2023
Grant date	Nov 14, 2023

Abstract

A fuel cell system that raises temperature of fuel cells by supplying heated air to the fuel cells during starting up period. The fuel cell system includes a plurality of fuel cells, a fuel supply path connected parallelly to the fuel cells to provide fuel thereto, an air supply path connected serially to the fuel cells to provide air thereto, a heat exchanger arranged in the fuel supply path to heat air or fuel, an air heat exchanger arranged in the air supply path to heat air; and a connection path connecting a position of the air supply path upstream to the air heat exchanger with a position of the fuel supply path upstream to the heat exchanger. A first control valve is arranged in the air supply path for controlling the air flowing into to the air heat exchanger. A second control valve arranged in the connection path for controlling the air flowing into the heat exchanger. The fuel cell system controls opening degrees of the first and second control valves during the start-up period of the fuel cell system to supply heated air to the fuel cells through both the air supply path and the fuel supply path.

First claim

The invention claimed is:

1. A fuel cell system configured to warm up a plurality of fuel cell stacks by providing heated air thereto during a start-up period, comprising:
the plurality of fuel cell stacks;
a fuel supply path connected in parallel to the fuel cell stacks and configured to connect a fuel source to the fuel cell stacks;
an air supply path connected in series to the fuel cell stacks and configured to connect an air source to the fuel cell stacks;
a heat exchanger arranged in the fuel supply path;
an air heat exchanger arranged in the air supply path;
a connection path branching from a position of the air supply path upstream of the air heat exchanger and connecting to a position of the fuel supply path upstream of the heat exchanger;
a first control valve arranged in a position of the air supply path, the first control valve controlling air flowing into the air heat exchanger;
a second control valve arranged in the connection path, the second control valve controlling air flowing into the heat exchanger; and
a controller programmed to control the first control valve and the second control valve; wherein:
the controller is programmed to control opening amounts of the first and second control valves so that a start-up control of the fuel cell stacks is performed in response to receiving a system startup command of the fuel cell system, the start-up control comprising supplying heated air to the fuel cell stacks through both the air supply path and the fuel supply path.

2. A fuel cell system according to claim 1 , further comprising a temperature sensor configured to obtain a detected temperature for each of the fuel cell stacks, wherein:
the controller is programmed to adjust the opening amounts of the first and second control valves based on the detected temperature.

3. A fuel cell system according to claim 1 , further comprising:
a bypass branching off from a position in the connection path or the air supply path, the position being upstream of the air heat exchanger, wherein:
the bypass is provided with a third control valve for controlling a supply of the air, the air being supplied to the fuel cell stacks without passing through the air heat exchanger during the start-up period of the fuel cell system.

4. A fuel cell system according to claim 3 , wherein:
the controller is programmed to:
until a time when a first fuel cell stack reaches a prescribed temperature during the start-up period of fuel cell system, control the opening amounts of the first and second control valve so that a rate of temperature increase of the first fuel cell stack becomes a highest rate of temperature increase of the fuel cell stacks, the first fuel cell stack being arranged closest of the fuel cell stacks to the air heat exchanger; and
from the time when the temperature of the first fuel cell stack reaches the prescribed temperature, control an opening amount of the third control valve to maintain a heat dissipation from the first fuel cell stack to the air flowing in from the air supply path such that the heat dissipation is equal to or greater than a heating amount provided to the first fuel cell stack by the air flowing in from the fuel supply path.

5. A fuel cell system according to claim 3 , wherein:
the controller is programmed to:
until a time when the first fuel cell stack located closest to the air heat exchanger reaches a prescribed temperature during the start-up period of fuel cell system,
in response to a heat input to the heat exchanger being greater than a heat input to the air heat exchanger, control the opening amounts of the first and second control valves to maintain an air supply ratio equal to or greater than a value calculated by dividing the number of fuel cell stacks by a heat input ratio, the air supply ratio being an air amount supplied to the air heat exchanger divided by a total air amount supplied to the heat exchanger and the air heat exchanger, the heat input ratio being the heat input to the heat exchanger divided by a total heat input to the heat exchanger and the air heat exchanger,
in response to the heat input to the heat exchanger being smaller than the heat input to the air heat exchanger, control the opening amounts of the first and second control valves to maintain the air supply ratio equal to or greater than the heat input ratio; and
from the time when the temperature of the first cell stack reaches the prescribed temperature, control an opening amount of the third control valve to maintain a heat dissipation from the first fuel cell stack to the air supplied from the air supply path such that the heat dissipation is equal to or greater than a heating amount provided by the air supplied from the fuel supply path to the first fuel cell stack.

6. A fuel cell system according to claim 4 , wherein the controller is further programmed to control the opening amounts of the first, second, and third control valves to maintain the following two values mutually equal:
an air supply ratio of the heat exchanger divided by a total air amount supplied into the heat exchanger and the air heat exchanger under the condition that the third control valve is closed; and
the air supply ratio of the heat exchanger divided by a total air amount supplied into the heat exchanger, the air heat exchanger, and the bypass under the condition that the third control valve is opened.

7. A fuel cell system according to claim 4 , wherein:
the controller is programmed to:
until the time when the first fuel cell stack reaches the prescribed temperature during the start-up period of the fuel cell system, control the opening amounts of the first and second control valves to minimize a total pressure loss, which is a sum of an air pressure loss due to the fuel supply path and an air pressure loss due to the air supply path.

8. A control method of a fuel cell system having a plurality of fuel cell stacks, the control method comprising:
providing the plurality of fuel cell stacks;
providing a fuel supply path connected in parallel to the fuel cell stacks and configured to connect a fuel source to the fuel cell stacks;
providing an air supply path connected in series to the fuel cell stacks and configured to connect an air source to the fuel cell stacks;
providing a heat exchanger arranged in the fuel supply path;
providing an air heat exchanger arranged in the air supply path;
providing a connection path branching from a position of the air supply path upstream of the air heat exchanger and connecting to a position of the fuel supply path upstream of the heat exchanger;
providing a first control valve arranged in a position of the air supply path, the first control valve controlling air flowing into the air heat exchanger;
providing a second control valve arranged in the connection path, the second control valve controlling air flowing into the heat exchanger; and
controlling, by a controller, opening amounts of the first and second control valves to supply heated air to the fuel cell stacks through both the air supply path and the fuel supply path.

Assignees

• Nissan Motor

Inventors

• Ikeguchi Ken Bryan
• Chikugo Hayato

Classifications

• H01M8/04268 Primary

  Heating of fuel cells during the start-up of the fuel cells · CPC title

• H01M8/04014 Primary

  Heat exchange using gaseous fluids; Heat exchange by combustion of reactants · CPC title

• H01M8/04302

  applied during start-up · CPC title

• H01M8/249

  comprising two or more groupings of fuel cells, e.g. modular assemblies · CPC title

• Y02E60/50

  Fuel cells · CPC title