System and methods for determining a stack current request based on fuel cell operational conditions

Patent metadata

Field	Value
Publication number	US-11990656-B2
Application number	US-202217842566-A
Country	US
Kind code	B2
Filing date	Jun 16, 2022
Priority date	Jun 16, 2021
Publication date	May 21, 2024
Grant date	May 21, 2024

Abstract

A stack current controller may be configured to determine a stack current request based on a state of charge of a battery, an error based on a difference between an actual coolant temperature and a coolant temperature setpoint, or both. A plurality of stack current levels may be implemented corresponding to different battery state-of-charge thresholds. The determined stack current magnitude may be the lowest current magnitude that provides sufficient heat to maintain a coolant temperature at the coolant temperature setpoint or within the coolant temperature threshold. The determined stack current magnitude may be the highest current magnitude that provides sufficient power while maintaining a coolant temperature at the coolant temperature setpoint or within the coolant temperature threshold.

First claim

The invention claimed is:

1. A method for requesting a current magnitude from a fuel cell, the method comprising:
based at least on one of a battery state of charge, a coolant temperature, and a fan speed, selecting a process from among a plurality of processes including at least normal processing, smart idle processing, and smart ceiling processing;
operating under the selected process to request a current magnitude from the fuel cell; and
outputting by the fuel cell the requested current magnitude;
wherein:
normal processing comprises requesting the current magnitude from the fuel cell based at least on the battery state of charge and in a stepwise manner where each current magnitude step includes a debounce range with respect to at least one other current magnitude step;
smart idle processing comprises requesting the current magnitude from the fuel cell based at least on the battery state of charge and the coolant temperature, wherein the current magnitude requested is sufficiently high to raise the coolant temperature towards a smart idle coolant temperature setpoint; and
smart ceiling processing comprises requesting the current magnitude from the fuel cell based on at least the fan speed and the coolant temperature, wherein the current magnitude requested is sufficiently low to reduce the coolant temperature towards a smart ceiling coolant temperature setpoint.

2. The method according to claim 1 , wherein selecting the process comprises selecting normal processing based on the coolant temperature being within a coolant temperature threshold.

3. The method according to claim 1 , wherein selecting the process comprises selecting smart idle processing based on the battery state of charge being below a pre-determined battery state of charge threshold and is further based on the coolant temperature being below a coolant temperature threshold.

4. The method according to claim 1 , wherein selecting the process comprises selecting smart ceiling processing based on a fan speed being above a pre-determined fan speed and is further based on the coolant temperature being above a coolant temperature threshold.

5. The method according to claim 2 , wherein the normal processing comprises:
requesting by a controller an initial current magnitude corresponding to one of a first magnitude step, a second magnitude step, and a third magnitude step based on the battery state of charge being within one of a first battery state of charge range, a second battery state of charge range, and a third battery state of charge range, respectively;
outputting the requested initial current magnitude as the requested current magnitude by the fuel cell;
changing by the controller the requested current magnitude between the first current magnitude step corresponding to a maximum current magnitude the fuel cell can produce, the second current magnitude step corresponding to an intermediate current magnitude the fuel cell can produce, and the third current magnitude step corresponding to a minimum current magnitude the fuel cell can produce based on the battery state of charge and the debounce ranges; and
outputting the changed requested current magnitude by the fuel cell.

6. The method according to claim 5 , wherein a first upper state of charge threshold is associated with the first current magnitude step, a second lower state of charge threshold is associated with the second current magnitude step and the second lower state of charge threshold corresponds to a lower battery state of charge than the battery state of charge corresponding to the first upper state of charge threshold to create a first debounce range, a second upper state of charge threshold associated with the second current magnitude step, and a third lower state of charge threshold associated with the third current magnitude step and the third lower state of charge threshold corresponds to a lower battery state of charge than the battery state of charge corresponding to the second upper state of charge threshold to create a second debounce range, the method further comprising:
changing, by the controller, the requested current magnitude from the first current magnitude step to the second magnitude step in response to the battery state of charge exceeding the first upper state of charge threshold and outputting by the fuel cell the requested second current magnitude step;
changing, by the controller, the requested current magnitude from the second current magnitude step to the third magnitude step in response to the battery state of charge exceeding the second upper state of charge threshold and outputting by the fuel cell the requested third current magnitude step;
changing, by the controller, the requested current magnitude from the third current magnitude step to the second magnitude step in response to the battery state of charge falling below the third lower state of charge threshold and outputting by the fuel cell the requested second current magnitude step; and
changing, by the controller, the requested current magnitude from the second current magnitude step to the first magnitude step in response to the battery state of charge falling below the second lower state of charge threshold and outputting by the fuel cell the requested first current magnitude step.

7. The method according to claim 3 , wherein the smart idle processing comprises:
determining by a controller an error between the coolant temperature and the smart idle coolant temperature setpoint including whether the error increases over a time period, remains static over the time period, or decreases over the time period;
requesting by the controller an increase to the requested current magnitude output by the fuel cell based on the error being outside a threshold range and the error either increasing or remaining static and outputting by the fuel cell the requested increased current magnitude;
requesting by the controller an existing current magnitude output by the fuel cell based on the error being outside the threshold range and the error decreasing and outputting by the fuel cell the requested existing current magnitude; and
requesting by the controller a decreased current magnitude output by the fuel cell based on the error being within the threshold range and outputting by the fuel cell the requested decreased current magnitude.

8. The method according to claim 4 , wherein the smart ceiling processing comprises:
determining by a controller a ceiling current magnitude based at least on an ambient temperature;
determining by the controller whether the ceiling magnitude is greater than the current magnitude being output by the fuel cell;
requesting by the controller for the fuel cell to output the ceiling current magnitude based on the ceiling current magnitude being less than the current magnitude being output by the fuel cell;
determining by the controller whether a fan speed has been below a predetermined fan speed for a predetermined fan time period;
lowering by the controller the ceiling current magnitude requested from the fuel cell based on one of the fan speed being above the predetermine fan speed and the fan speed being below the predetermined fan speed but for less than the predetermined fan time period, requesting by the controller for the fuel cell to output the lowered ceiling current magnitude, and outputting by the fuel cell the lowered ceiling current magnitude;
determining by the controller whether the coolant temperature has been above a coolant temperature threshold for a predetermined coolant time period;
lowering by the controller the ceiling current magnitude requested from the fuel cell based on one of the coolant temperature being above the coolant temperature threshold and the coolant temperature being below

Assignees

• Hyster Yale Group Inc

Inventors

• Bryant Jacob
• Robey John
• Fox Troy
• Chen Chenyao
• Hossainy Tabassum
• Brisbine David

Classifications

• H01M8/0491 Primary

  of fuel cell stacks · CPC title

• H01M8/04358

  of the coolant · CPC title

• H01M2250/20

  Fuel cells in motive systems, e.g. vehicle, ship, plane · CPC title

• H01M8/04395

  of cathode reactants at the inlet or inside the fuel cell · CPC title

• H01M8/04626

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