Solid oxide fuel cell system

Patent metadata

Field	Value
Publication number	US-9379399-B2
Application number	US-201114347983-A
Country	US
Kind code	B2
Filing date	Sep 29, 2011
Priority date	Sep 29, 2011
Publication date	Jun 28, 2016
Grant date	Jun 28, 2016

Abstract

To provide a solid oxide fuel cell system capable of efficiently and simply controlling a low speed fuel cell module and a high speed inverter. The invention is a solid oxide fuel cell system, comprising: a fuel cell module, a fuel flow regulator unit, a control section comprising a first power demand detection circuit for controlling the fuel supply amount and for setting the value of current extractable from the fuel cell module; an inverter for extracting current from fuel cell module; and a second power demand detection circuit; and having an inverter control section for controlling the inverter independently from the fuel cell controller so that a current responsive to power demand is extracted from the fuel cell module in a range not exceeding the extractable current value input from the fuel cell controller.

First claim

The invention claimed is:

1. A solid oxide fuel cell system for generating electrical power variable in response to power demand, comprising:
a fuel cell module configured to generate electricity by reaction of supplied fuel;
a fuel supply device configured to supply the fuel to the fuel cell module;
an inverter operable to extract electrical current from the fuel cell module and output the current in alternating form;
a fuel cell controller circuit comprising a first power demand detection circuit configured to detect power demand, the fuel cell controller circuit being programmed to:
from the power demand detected by the first power demand detection circuit, generate a target fuel supply signal, indicative of a target amount of fuel supply, which operates the fuel supply device to supply the target amount of fuel to the fuel cell module so that the fuel cell module generates electricity sufficient to follow transitions of the power demand; and
from the power demand detected by the first power demand detection circuit, generate an extractable current value signal, indicative of a maximum current value extractable from the fuel cell module; and

an inverter controller circuit provided separately from the fuel cell controller circuit and including a second power demand detection circuit configured to detect the power demand independently from the first power demand detection circuit,
wherein the inverter controller circuit is programmed to operate the inverter in response to the extractable current value signal from the fuel cell controller circuit and the power demand detected by the second power demand detection circuit to (i) remain under control of the extractable current value signal so as to not extract current from the fuel cell module more than the maximum extractable current value and (ii) upon a decrease of the power demand detected by the second power demand detection circuit, move out of the control of the extractable current value signal to reduce extraction of the current from the fuel cell module independently from the extractable current value signal.

2. The solid oxide fuel cell system according to claim 1 , wherein the fuel cell controller circuit further comprises an extracted current detection circuit configured to detect the extracted current from the fuel cell module, and the fuel cell controller circuit is programmed to change the extractable current value signal so that the maximum extractable current value drops to the detected extracted current when the detected extracted current drops from the maximum extractable current value by more than a first predetermined current value.

3. The solid oxide fuel cell system according to claim 2 , wherein the fuel cell controller circuit is programmed to change the target fuel supply signal to reduce the target amount of fuel supply some delay time after it changes the extractable current value signal to decrease the maximum extractable current value.

4. The solid oxide fuel cell system according to claim 3 , wherein the fuel cell controller circuit is programmed to change the extractable current value signal to raise the maximum extractable current value at a first rate when a current equivalent to the target amount of fuel supply is greater than the detected extracted current by a threshold value or less and raise the maximum extractable current value at a second rate higher than the first rate when the current equivalent to the target amount of fuel supply is greater than the detected extracted current by more than the threshold value.

5. The solid oxide fuel cell system according to claim 1 , wherein the inverter controller circuit operates at a clock speed faster than a clock speed at which the fuel cell controller circuit operates.

6. The solid oxide fuel cell system according to claim 2 , wherein the fuel cell controller circuit is programmed to change the extractable current value signal so that the maximum extractable current value decreases progressively while a difference between the detected extracted current and the maximum extractable current value is less than or equal to the predetermined current value.

7. The solid oxide fuel cell system according to claim 2 , wherein the fuel cell controller circuit is programmed to decreases the maximum extractable current value when one of a first set of operation conditions is satisfied, the first set of operation conditions including at least one of (i) degradation of the fuel cell module, (ii) power output above a rated power, (iii) high operation temperature of the fuel cell module, (iv) low operation temperature of the fuel cell or (v) low current extraction from the fuel cell module.

8. The solid oxide fuel cell system according to claim 4 , wherein the fuel cell controller circuit is programmed to raise the maximum extractable current value when all of a second set of operation conditions are satisfied, the second set of operation conditions including at least one of (i) the current equivalent to the target amount of fuel supply being equal to or less than the detected extracted current by a threshold current value, (ii) an output voltage from the fuel cell module being equal to or higher than a threshold voltage value, (iii) an interconnect power being equal to or lower than a threshold interconnect power value, (iv) a fuel cell module temperature being equal to or higher than a threshold temperature value and (v) a grid power being higher than a threshold grid power value.

9. The solid oxide fuel cell system according to claim 8 , wherein the fuel cell controller circuit is programmed to leave the maximum extractable current value unchanged when any of the second set of operation conditions is not satisfied.

Assignees

• Otsuka Toshiharu
• Tsuchiya Katsuhisa
• Shigezumi Tsukasa
• Ooe Toshiharu
• Nakano Kiyotaka
• Matsuo Takuya
• Toto Ltd

Inventors

• Otsuka Toshiharu
• Tsuchiya Katsuhisa
• Shigezumi Tsukasa
• Ooe Toshiharu
• Nakano Kiyotaka
• Matsuo Takuya

Classifications

• H01M8/04753

  of fuel cell reactants · CPC title

• Y02E60/525

  Cross-Sectional Technologies · mapped topic

• Y02E60/50

  Fuel cells · CPC title

• H01M8/04626 Primary

  of auxiliary devices, e.g. batteries, capacitors · CPC title

• H01M8/04902 Primary

  of the individual fuel cell · CPC title