Fuel cell-battery system and control method thereof

1. A fuel cell-battery system comprising:

a battery module including a battery configured to store electric power and a coolant line through which coolant circulates to cool the battery;

a fuel cell module including a hydrogen tank configured to store hydrogen, a fuel cell configured to produce the electric power using the hydrogen, and a hydrogen line configured to connect the hydrogen tank and the fuel cell to deliver the hydrogen from the hydrogen tank to the fuel cell; and

a heat exchange module through which the coolant line and the hydrogen line pass such that the coolant is cooled by heat exchange with the hydrogen and the hydrogen is heated by heat exchange with the coolant,

wherein the fuel cell module further includes

an external heat exchanger disposed on the hydrogen line between the heat exchange module and the hydrogen tank and configured to heat the hydrogen flowing in the hydrogen line, and

a return line configured to return the hydrogen passing through the external heat exchanger to an upstream side of the external heat exchanger with respect to a direction in which the hydrogen flows in the hydrogen line.

2. The fuel cell-battery system of claim 1 , wherein the battery module further includes:

a heater configured to heat the coolant; and

a heating line configured to pass through the heater to heat the coolant.

3. The fuel cell-battery system of claim 2 , wherein the battery module further includes:

a coolant temperature acquisition device configured to obtain temperature of the coolant released from the battery; and

a battery controller electrically connected with the coolant temperature acquisition device and the heater, and

wherein the battery controller:

performs control such that the coolant flows along the coolant line and the heater stops operating, when the obtained coolant temperature is higher than a target coolant temperature; and

performs control such that the coolant flows along the heating line and the heater operates, when the obtained coolant temperature is lower than the target coolant temperature.

4. The fuel cell-battery system of claim 3 , wherein the battery controller performs control such that the coolant flows along the heating line and the heater stops operating, when the obtained coolant temperature is equal to the target coolant temperature.

5. The fuel cell-battery system of claim 1 , wherein the fuel cell module further includes:

a hydrogen temperature acquisition device configured to obtain temperature of the hydrogen passing through the external heat exchanger; and

a fuel cell controller electrically connected with the hydrogen temperature acquisition device,

wherein the hydrogen tank includes a hydrogen reservoir in which the hydrogen is stored and an internal heat exchanger through which the hydrogen reservoir and an introduced material exchange heat with each other, and

wherein the fuel cell controller:

returns the hydrogen to the internal heat exchanger through the return line to cool the hydrogen, when the obtained hydrogen temperature is higher than or equal to an upper limit of a target hydrogen temperature range; and

returns the hydrogen to the external heat exchanger through the return line to heat the hydrogen, when the obtained hydrogen temperature is lower than or equal to a lower limit of the target hydrogen temperature range.

6. A fuel cell-battery system comprising:

a battery module including a battery configured to store electric power and a coolant line through which coolant circulates to cool the battery;

a fuel cell module including a hydrogen tank configured to store hydrogen, a fuel cell configured to produce the electric power using the hydrogen, and a hydrogen line configured to connect the hydrogen tank and the fuel cell to deliver the hydrogen from the hydrogen tank to the fuel cell; and

a heat exchange module through which the coolant line and the hydrogen line pass such that the coolant is cooled by heat exchange with the hydrogen and the hydrogen is heated by heat exchange with the coolant,

wherein the battery module further includes a coolant temperature acquisition device configured to obtain temperature of the coolant released from the battery and a battery controller electrically connected with the coolant temperature acquisition device,

wherein the fuel cell module further includes a bypass line through which the hydrogen in the hydrogen line is bypassed to the fuel cell before entering the heat exchange module and a fuel cell controller electrically connected to the coolant temperature acquisition device and the battery controller, and

wherein the fuel cell controller

allows the hydrogen to pass through the heat exchange module, when the obtained coolant temperature is higher than a target coolant temperature and

allows the hydrogen to flow along the bypass line, when the obtained coolant temperature is lower than or equal to the target coolant temperature.

7. The fuel cell-battery system of claim 1 , wherein the fuel cell module further includes a circulation line through which the hydrogen returns to the hydrogen tank before the hydrogen enters the fuel cell after passing through the heat exchange module.

8. The fuel cell-battery system of claim 1 , wherein the fuel cell module further includes a regulator disposed in the hydrogen line and configured to reduce pressure of the hydrogen flowing in the hydrogen line to locate the pressure of the hydrogen to be supplied to the fuel cell within a predetermined pressure range.

9. The fuel cell-battery system of claim 1 , wherein the heat exchange module is one of a coaxial pipe heat exchanger, a fin-tube heat exchanger, and a plate heat exchanger that are formed such that the hydrogen and the coolant indirectly exchange heat with each other.

10. The fuel cell-battery system of claim 1 , wherein the heat exchange module includes:

a main heat exchange module through which coolant of the battery module and hydrogen of the fuel cell module exchange heat with each other; and

an additional heat exchange module through which coolant of at least one of a vehicle air-conditioning system, a fuel cell stack, or an engine exchanges heat with hydrogen of the fuel cell module.

11. The fuel cell-battery system of claim 1 , wherein the storage tank is a cryo-compressed hydrogen storage.