FUEL CELL SYSTEM FREEZE-START SYSTEMS AND METHODS
The present disclosure provides a method for heating a dual stack fuel cell system of a vehicle. The method may include receiving a heat power request from a first fuel cell stack, receiving a first temperature of the first fuel cell stack and a second temperature of a second fuel cell stack, initiating, responsive to the first temperature and the second temperature indicating that the first fuel cell stack and the second fuel cell stack are frozen, a freeze-start thermal operating mode for the first fuel cell stack, and transferring, during the freeze-start thermal operating mode for the first fuel cell stack, heat from a brake resistor to the first fuel cell stack.
1 . A method for heating a dual stack fuel cell system of a vehicle, the method comprising:
receiving a heat power request from a first fuel cell stack;
receiving a first temperature of the first fuel cell stack and a second temperature of a second fuel cell stack;
initiating, responsive to the first temperature and the second temperature indicating that the first fuel cell stack and the second fuel cell stack are frozen, a freeze-start thermal operating mode for the first fuel cell stack; and
transferring, during the freeze-start thermal operating mode for the first fuel cell stack, heat from a brake resistor to the first fuel cell stack.
2 . The method of claim 1 , wherein the first temperature is a measured coolant temperature at an outlet of the first fuel cell stack and the second temperature is a measured coolant temperature at an outlet of the second fuel cell stack.
3 . The method of claim 1 , further comprising comparing the heat power request to a threshold power value.
4 . The method of claim 1 , further comprising commanding, during the freeze-start thermal operating mode for the first fuel cell stack, a brake resistor power to a maximum operating power.
5 . The method of claim 1 , further comprising comparing the first temperature and the second temperature to a first threshold temperature to determine if the first fuel cell stack and the second fuel cell stack are frozen.
6 . The method of claim 4 , further comprising setting, during the freeze-start thermal operating mode for the first fuel cell stack, a coolant temperature setpoint at an outlet of the brake resistor.
7 . The method of claim 6 , further comprising controlling, during the freeze-start thermal operating mode for the first fuel cell stack, the brake resistor power based on the coolant temperature setpoint at the outlet of the brake resistor.
8 . The method of claim 1 , further comprising receiving a third temperature of the first fuel cell stack and a fourth temperature of the second fuel cell stack.
9 . The method of claim 8 , further comprising terminating, responsive to the third temperature or the fourth temperature being greater than or equal to a second threshold temperature, the freeze-start thermal operating mode for the first fuel cell stack.
10 . A method for heating a dual stack fuel cell system of a vehicle, the method comprising:
receiving a heat power request from a first fuel cell stack;
receiving a first temperature of the first fuel cell stack and a second temperature of a second fuel cell stack;
determining a first thermal state of the first fuel cell stack using the first temperature and a second thermal state of the second fuel cell stack using the second temperature;
initiating, responsive to the first thermal state being a frozen thermal state and the second thermal state being an operable thermal state, a freeze-start thermal operating mode for the first fuel cell stack; and
transferring, during the freeze-start thermal operating mode for the first fuel cell stack, heat from the second fuel cell stack to the first fuel cell stack.
11 . The method of claim 10 , further comprising transferring, during the freeze-start thermal operating mode for the first fuel cell stack, heat from a brake resistor to the first fuel cell stack.
12 . The method of claim 10 , further comprising commanding, during the freeze-start thermal operating mode for the first fuel cell stack, a first valve to a fully open position and a second valve to a fully open position.
13 . The method of claim 12 , wherein the first valve is positioned between the first fuel cell stack and a first coolant-coolant heat exchanger, and the second valve is positioned between the second fuel cell stack and a second coolant-coolant heat exchanger.
14 . The method of claim 13 , wherein the first valve permits a first coolant to pass through the first coolant-coolant heat exchanger when in the fully open position, and wherein the second valve permits a second coolant to pass through the second coolant-coolant heat exchanger when in the fully open position.
15 . The method of claim 11 , further comprising commanding a brake resistor power to a maximum operating power.
16 . The method of claim 11 , further comprising commanding a pump speed of a pump in a brake resistor coolant loop to a maximum speed.
17 . The method of claim 11 , further comprising setting a coolant temperature at an outlet of the brake resistor.
18 . A method of heating a dual stack fuel cell system of a vehicle, the method comprising:
receiving a first temperature of a first fuel cell stack and a second temperature of a second fuel cell stack;
determining a first thermal state of the first fuel cell stack using the first temperature and a second thermal state of the second fuel cell stack using the second temperature; and
commanding, responsive to a determination that the first thermal state is a frozen state and the second thermal state is a frozen state, a first valve to an open position to enable heat transfer from a brake resistor to the first fuel cell stack.
19 . The method of claim 18 , further comprising comparing the first temperature and the second temperature to a threshold temperature to determine the first thermal state and the second thermal state.
20 . The method of claim 18 , wherein the first valve is positioned between the first fuel cell stack and a coolant-coolant heat exchanger thermally coupled to the brake resistor.