Equation based cooling system control strategy/method

A system for heating or cooling a fuel cell circuit of a vehicle comprising:

• a fuel cell stack having a plurality of fuel cells and configured to receive a fluid and to heat the fluid;
• a temperature sensor configured to detect a fluid temperature of the fluid;
• a radiator configured to remove thermal energy from at least some of the fluid;
• a fan configured to force a gas towards the radiator to increase heat transfer from the fluid to the gas;
• and
• an electronic control unit (ECU) coupled to the temperature sensor and the pump and configured to:
• determine a temperature control signal based on the fluid temperature of the fluid,
• calculate a desired amount of thermal energy to be removed from the radiator by the fan based on the temperature control signal,
• calculate a desired fan speed of the fan to achieve the desired amount of thermal energy to be removed from the radiator by the fan based on the desired amount of thermal energy to be removed from the radiator by the fan, and
• control the fan to operate at the desired fan speed.

A method for heating or cooling a fuel cell circuit of a vehicle comprising:

• receiving and heating, by a fuel cell stack having a plurality of fuel cells, a fluid;
• detecting, by a temperature sensor, a fluid temperature of the fluid;
• determining, by an electronic control unit (ECU), a temperature control signal based on the fluid temperature of the fluid;
• calculating, by the ECU, a desired fluid ratio corresponding to a desired percentage of a flow of the fluid that is received by a radiator of the fuel cell circuit to a total flow of the fluid through the radiator and through a bypass branch that bypasses the radiator based on the temperature control signal,
• determining, by the ECU, a desired valve position of a three-way valve based on the desired fluid ratio;
• and
• controlling, by the ECU, the three-way valve to have the desired valve position such that the three-way valve achieves the desired fluid ratio.