Fuel cell propulsion system with a fuel cell stack for a motor vehicle and process for controlling a temperature of the fuel cell stack

A fuel cell propulsion system for a motor vehicle, the fuel cell propulsion system comprising:

• a fuel cell stack for generating an electrical current with an associated waste heat;
• a coolant passage having a coolant section coupled to the fuel cell stack and flowing a coolant through the fuel cell stack for removing the waste heat, with the coolant passage further including an inlet positioned upstream of the coolant section and an outlet positioned downstream of the coolant section;
• at least one temperature sensor attached to the coolant passage at the inlet or at the outlet of the coolant section and generating a temperature signal associated with a temperature of the coolant at the inlet or at the outlet;
• at least one pressure sensor attached to the coolant section of the coolant passage and generating a pressure signal associated with a pressure drop across the fuel cell stack;
• a computer comprising:
• at least one processor;
• and
• a non-transitory computer readable storage medium including instructions such that the at least one processor is programmed to:
• determine a feedback correction based on the pressure drop of the coolant across the fuel cell stack and the temperature of the coolant in response to the at least one processor receiving the temperature signal from the at least one temperature sensor and the pressure signal from the at least one pressure sensor, wherein the feedback correction is an adjustment calculated using a proportional integral controller to meet a target flow rate of the coolant;
• and
• generate a pump command signal by summing the feedback correction with a nominal pump command;
• and
• a pump fluidly connected to the coolant passage and operating at a target pump speed for pumping the coolant through the coolant passage at the target flow rate in response to the pump receiving the pump command signal from the at least one processor.

A process of operating a fuel cell propulsion system for a motor vehicle, with the fuel cell propulsion system including a fuel cell stack, a coolant passage having a coolant section coupled to the fuel cell stack and flowing a coolant through the fuel cell stack, with the coolant passage further including an inlet positioned upstream of the coolant section and an outlet positioned downstream of the coolant section, at least one temperature sensor attached to the inlet or to the outlet of the coolant section, at least one pressure sensor attached to the coolant passage, a pump, and a computer having at least one processor and a non-transitory computer readable storage medium for storing instructions, the process comprising:

• generating, using the fuel cell stack, an electrical current with an associated waste heat;
• flowing the coolant through the coolant passage;
• generating, using the at least one temperature sensor, a temperature signal associated with a temperature of the coolant at either the inlet or the outlet;
• generating, using the at least one pressure sensor, a pressure signal associated with a pressure drop of the coolant across the fuel cell stack;
• determining, using the at least one processor, a feedback correction based on the pressure drop of the coolant across the fuel cell stack and the temperature of the coolant in response to the at least one processor receiving the temperature signal from the at least one temperature sensor and the pressure signal from the at least one pressure sensor, wherein the feedback correction is an adjustment calculated using a proportional integral controller to meet a target flow rate of the coolant;
• generating a pump command signal by summing the feedback correction and a nominal pump command;
• and
• operating the pump at a target pump speed determined by the pump command signal to pump the coolant through the coolant passage at the target flow rate.