# US 9,437,888 B2 · Fuel cell system and control method therefor

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- Number: US 9,437,888 B2
- Document ID: US9437888B2
- Status: Granted
- Kind: B2
- Application number: 13/520,044
- Filed: 2010-12-13
- Published: 2012-11-01
- Granted: 2016-09-06
- Earliest claimed: 2010-01-18
- Assignees: Toyota Jidosha Kabushiki Kaisha
- Applicants: Michio Yoshida; Yuji Kakeno; Tomoya Ogawa; Hiromitsu Kawamori
- Inventors: Michio Yoshida; Yuji Kakeno; Tomoya Ogawa; Hiromitsu Kawamori
- Web page: https://patentgrep.com/patent/US9437888B2

## CPC

- H01M 8/04544: {Voltage}
- B60L 58/30: for monitoring or controlling fuel cells
- H01M 8/04574: {Current}
- H01M 8/04604: {Power, energy, capacity or load}
- H01M 8/04865: {Voltage}
- H01M 8/04895: {Current}
- H01M 8/04925: {Power, energy, capacity or load}
- H01M 10/44: Methods for charging or discharging (circuits for charging H02J7/00)
- H01M 10/46: Accumulators structurally combined with charging apparatus (circuits for charging H02J7/00)
- H01M 16/006: {of fuel cells with rechargeable batteries}
- H01M 2250/20: Fuel cells in motive systems, e.g. vehicle, ship, plane
- Y02E 60/10: Energy storage using batteries
- Y02E 60/50: Fuel cells
- Y02T 10/70: Energy storage systems for electromobility, e.g. batteries
- Y02T 90/40: Application of hydrogen technology to transportation, e.g. using fuel cells
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

During an intermittent operation of the fuel cell, a demanded FC voltage calculation portion calculates a predetermined voltage that is below a heightened potential avoidance threshold voltage as a demanded FC voltage, and outputs the voltage to a converter. When during the intermittent operation of the fuel cell, a deviation obtained by subtracting a generated power of the fuel cell from a system's allowable power that is allowable in the fuel cell system becomes less than or equal to a value 0, the demanded FC voltage correction portion corrects a command value provided for the converter so that the deviation becomes equal to the value 0.

## Claims

### Claim 1

A fuel cell system that includes a fuel cell and a secondary cell, and that supplies electric power to a load, comprising:
a converter that controls output voltage of the fuel cell; and
a high-potential avoidance control portion that restrains output voltage of the fuel cell from becoming greater than or equal to a predetermined heightened potential avoidance threshold voltage that is lower than an open-circuit voltage of the fuel cell by controlling a command value provided for the converter during an intermittent operation of the fuel cell, wherein
the high-potential avoidance control portion includes a converter command value correction portion that corrects the command value for the converter so that a deviation obtained by subtracting a generated power of the fuel cell from a system's allowable power that is allowable in the fuel cell system becomes equal to a value 0 when the deviation is below the value 0,
wherein a demanded fuel cell voltage setting portion that sets a predetermined voltage that is below the predetermined heightened potential avoidance threshold voltage, as a demanded fuel cell voltage,
wherein a voltage correction value calculation portion that, when the deviation is less than or equal to zero, calculates a voltage correction value MV that is an amount of operation for causing the fuel cell generated power to be equal to the system's allowable power, and when the deviation exceeds zero, set a voltage correction value MV at zero, and
wherein a converter command voltage output portion that outputs a value obtained by adding a demanded fuel cell voltage Vrf set by the demanded fuel cell voltage setting portion to the voltage correction value MV as a converter command voltage to the converter.

### Claim 2 (depends on 1)

The fuel cell system according to claim 1, wherein the converter command value correction portion obtains the system's allowable power by summing a demanded power of the fuel cell system and a charging power restriction value regarding the secondary cell.

### Claim 3 (depends on 1)

The fuel cell system according to claim 1, further comprising
an output detection portion that detects output current of the fuel cell or the output voltage of the fuel cell, wherein
the converter command value correction portion includes:
a feedback control portion that performs a feedback control based on the deviation;
a determination portion that determines which one of two sections of a current-voltage curve of the fuel cell divided by a bend point, at which a curvature of the current-voltage curve reaches a maximum value, contains a point of the output current or the output voltage detected by the output detection portion; and
a gain switching portion that switches gain of the feedback control based on a result of determination of the determination portion,
wherein a plurality of the current-voltage curves is stored, each of the current-voltage curves is set in accordance with a temperature of the fuel cell, and each of the current-voltage curves has the bend point which varies in accordance with the temperature of the fuel cell, and
wherein a first gain value and a second gain value of the feedback control is stored, each of the first gain value and the second gain value is set in accordance with the output current of the fuel cell or the output voltage of the fuel cell, and the gain switching portion selects the first gain.

### Claim 4

A fuel cell system that includes a fuel cell and a secondary cell, and that supplies electric power to a load, comprising:
a converter that controls output voltage of the fuel cell; and
a high-potential avoidance control portion that, during an intermittent operation of the fuel cell, restrains output voltage of the fuel cell from becoming greater than or equal to a predetermined heightened potential avoidance threshold voltage that is lower than an open-circuit voltage of the fuel cell, by controlling a command value provided for the converter, wherein
the high-potential avoidance control portion includes a converter command value correction portion that corrects the command value for the converter so that a deviation obtained by subtracting an output voltage of the secondary cell from an upper-limit voltage of the secondary cell becomes equal to a value 0 when the deviation is lower than the value 0,
wherein a demanded fuel cell voltage setting portion that sets a predetermined voltage that is below the predetermined heightened potential avoidance threshold voltage, as a demanded fuel cell voltage,
wherein a voltage correction value calculation portion that, when the deviation is less than or equal to zero, calculates a voltage correction value MV that is an amount of operation for causing the fuel cell generated power to be equal to the system's allowable power, and when the deviation exceeds zero, set a voltage correction value MV at zero, and
wherein a converter command voltage output portion that outputs a value obtained by adding a demanded fuel cell voltage Vrf set by the demanded fuel cell voltage setting portion to the voltage correction value MV, as a converter command voltage to the converter.

### Claim 5

A fuel cell system that includes a fuel cell and a secondary cell, and that supplies electric power to a load, comprising:
a converter that controls output voltage of the fuel cell; and
a high-potential avoidance control portion that restrains output voltage of the fuel cell from becoming greater than or equal to a predetermined heightened potential avoidance threshold voltage that is lower than an open-circuit voltage of the fuel cell by controlling a command value provided for the converter during an intermittent operation of the fuel cell, wherein
the high-potential avoidance control portion includes a converter command value correction portion that corrects the command value for the converter so that a deviation obtained by subtracting an output current of the secondary cell from a lower-limit current of the secondary cell becomes equal to a value 0 when the deviation is greater than the value 0,
wherein a demanded fuel cell voltage setting portion that sets a predetermined voltage that is below the predetermined heightened potential avoidance threshold voltage, as a demanded fuel cell voltage,
wherein a voltage correction value calculation portion that, when the deviation is less than or equal to zero, calculates a voltage correction value MV that is an amount of operation for causing the fuel cell generated power to be equal to the system's allowable power, and when the deviation exceeds zero, set a voltage correction value MV at zero, and
wherein a converter command voltage output portion that outputs a value obtained by adding a demanded fuel cell voltage Vrf set by the demanded fuel cell voltage calculation portion to the voltage correction value MV as a converter command voltage to the converter.

### Claim 6

A fuel cell system that includes a fuel cell and a secondary cell, and that supplies electric power to a load, comprising:
a converter that controls output voltage of the fuel cell;
a converter command value correction portion that performs a feedback control of a correction value for a command value provided for the converter based on a deviation obtained by subtracting a generated electric power of the fuel cell from a demanded output electric power of the fuel cell, and that adds the correction value to the command value provided for the converter; and
an output detection portion that detects output current of the fuel cell or the output voltage of the fuel cell, wherein
the converter command value correction portion includes: a determination portion that determines which one of two sections of a current-voltage curve of the fuel cell divided by a bend point contains a point of an output current or an output voltage of the fuel cell detected by the output detection portion; and a gain switching portion that switches gain of the feedback control based on a result of determination of the determination portion,
wherein a plurality of the current-voltage curves is stored, each of the current-voltage curves is set in accordance with a temperature of the fuel cell, and each of the current-voltage curves has the bend point which varies in accordance with the temperature of the fuel cell, and
wherein a first gain value and a second gain value of the feedback control is stored, each of the first gain value and the second gain value is set in accordance with the output current of the fuel cell or the output voltage of the fuel cell, and the gain switching portion selects the first gain.

### Claim 7

A control method for a fuel cell system that includes: a fuel cell; a secondary cell; and a converter which controls output voltage of the fuel cell, and that supplies electric power to a load,
the control method comprising:
restraining the output voltage of the fuel cell from becoming a greater than or equal to a predetermined heightened potential avoidance threshold voltage that is lower than an open-circuit voltage of the fuel cell by controlling a command value provided for the converter during an intermittent operation of the fuel cell;
obtaining a deviation by subtracting a generated power of the fuel cell from a system's allowable power that is allowable in the fuel cell system;
correcting the command value for the converter so that the deviation becomes equal to a value 0 when the deviation is less than the value 0;
setting a predetermined voltage that is below the predetermined heightened potential avoidance threshold voltage, as a demanded fuel cell voltage;
when the deviation is less than or equal to zero, calculating a voltage correction value MV that is an amount of operation for causing the fuel cell generated power to be equal to the system's allowable power, and when the deviation exceeds zero, setting a voltage correction value MV at zero, and
outputting a value obtained by adding a demanded fuel cell voltage Vrf to the voltage correction value MV as a converter command voltage to the converter.