Fuel cell architectures, thermal systems, and control logic for efficient heating of fuel cell stacks

A motor vehicle comprising:

• a vehicle body with a plurality of road wheels;
• a traction motor attached to the vehicle body and configured to drive one or more of the road wheels;
• a fuel cell system operable to power the traction motor and including first and second fluid control devices and a fuel cell stack with a cathode side, an anode side, and a membrane disposed between the cathode and anode sides, the first fluid control device being configured to direct hydrogen flow to the anode side and/or the cathode side, and the second fluid control device being configured to direct oxygen flow to the cathode side;
• and
• a vehicle controller attached to the vehicle body and programmed to:
• determine a pre-start temperature of the fuel cell stack;
• determine, for the pre-start temperature, a target heating rate to heat the fuel cell stack to a calibrated minimum stack operating temperature;
• determine a hydrogen bleed percentage for the determined target heating rate;
• execute a stack heating operation including activating the fuel cell stack and commanding the first fluid control device to direct hydrogen to the cathode side at the hydrogen bleed percentage such that waste heat is generated;
• determine, after a calibrated period of time of executing the stack heating operation, if an operating temperature of the fuel cell stack is at or above the calibrated minimum stack operating temperature;
• and
• responsive to a determination that the operating temperature is at or above the calibrated minimum stack operating temperature, disengaging the stack heating operation.

A non-transitory, computer readable medium storing instructions for execution by an onboard vehicle controller of a motor vehicle, the motor vehicle having a plurality of road wheels, a traction motor configured to drive one or more of the road wheels, and a fuel cell system with a fuel cell stack operable to power the traction motor, the instructions causing the vehicle controller to perform steps comprising:

• determining a pre-start temperature of the fuel cell stack;
• determining, for the pre-start temperature, a target heating rate to heat the fuel cell stack to a calibrated minimum stack operating temperature;
• determining a hydrogen bleed percentage for the determined target heating rate;
• executing a stack heating operation including activating the fuel cell stack and commanding a first fluid control device to direct hydrogen to a cathode side of the fuel cell stack at the hydrogen bleed percentage such that the fuel cell stack generates waste heat;
• determining, after a calibrated period of time of executing the stack heating operation, if an operating temperature of the fuel cell stack is at or above the calibrated minimum stack operating temperature;
• and
• responsive to a determination that the operating temperature is at or above the calibrated minimum stack operating temperature, disengaging the stack heating operation.