Method of operating a cooling system having dual independent refrigerant loops for providing cooling to a vehicle cabin and vehicle battery

1. A method of operating a cooling system for a vehicle comprising:

providing the cooling system comprising:

a coolant loop configured to exchange heat with a battery;

a first refrigerant loop comprising a first compressor, an evaporator configured to exchange heat with a cabin of said vehicle, an evaporator shutoff valve, a first chiller configured to exchange heat with the coolant loop, and a first chiller shutoff valve; and

a second refrigerant loop comprising a second compressor and a second chiller configured to exchange heat with the coolant loop, wherein the coolant loop comprises a coolant valve for selectively directing or preventing the flow of a coolant between the battery and each of the first chiller and the second chiller;

providing a cooling system controller operably coupled to the first compressor, the second compressor, the coolant valve, the evaporator shutoff valve, and the first chiller shutoff valve;

determining cooling capabilities of each of the first refrigerant loop and the second refrigerant loop;

determining cabin cooling needs and battery cooling needs;

adjusting the coolant valve to selectively direct or prevent the flow of the coolant to at least one of the first chiller and the second chiller;

adjusting the coolant valve to direct the coolant to the first chiller and prevent the flow of the coolant to the second chiller when cabin cooling is needed and the combined cooling needs of the cabin and the battery are less than the cooling capability of the first refrigerant loop;

modifying a speed of at least one of the first compressor and the second compressor to satisfy the cabin cooling needs and the battery cooling needs; and

determining a combined coefficient of performance (COP) optimization for the first compressor and the second compressor and modifying the speed of the first compressor and the second compressor according to the combined COP optimization.

2. The method of claim 1 , further comprising adjusting the coolant valve to direct coolant to the second chiller and prevent the flow of coolant to the first chiller when cabin cooling is not needed and the battery cooling needs are less than the cooling capability of the second refrigerant loop.

3. The method of claim 1 , further comprising adjusting the coolant valve to prevent the flow of the coolant to the first chiller and the second chiller and adjusting the evaporator shutoff valve and the first chiller shutoff valve to direct the flow of refrigerant in the first refrigerant loop to the evaporator and prevent the flow of refrigerant to the first chiller when cabin cooling is needed and battery cooling is not needed.

4. The method of claim 1 , further comprising adjusting the coolant valve to direct the coolant to the first chiller and the second chiller when the combined cooling needs of the cabin and the battery exceed the cooling capability of each of the first refrigerant loop and the second refrigerant loop.

5. The method of claim 1 , further comprising determining noise, vibration, and harshness (NVH) limits for the first compressor and the second compressor and modifying the speed of the first compressor and the second compressor according to the NVH limits.

6. A method of operating a cooling system for a vehicle comprising:

providing the cooling system including a coolant loop configured to exchange heat with a battery; a first refrigerant loop comprising a first compressor, an evaporator configured to exchange heat with a cabin of said vehicle, an evaporator shutoff valve, a first chiller configured to exchange heat with the coolant loop, and a first chiller shutoff valve; and a second refrigerant loop comprising a second compressor and a second chiller configured to exchange heat with the coolant loop, wherein the coolant loop comprises a coolant valve for selectively directing or preventing the flow of a coolant between the battery and each of the first chiller and the second chiller;

providing a cooling system controller operably coupled to the first compressor, the second compressor, the coolant valve, the evaporator shutoff valve, and the first chiller shutoff valve;

determining cabin cooling needs and battery cooling needs;

operating the cooling system in one of a second chiller only mode, a first chiller only mode, an air conditioning (AC) only mode, a first refrigerant loop only mode, and a dual refrigerant loop mode;

modifying a speed of at least one of the first compressor and the second compressor to satisfy the cabin cooling needs and the battery cooling needs; and

determining a combined coefficient of performance (COP) optimization for the first compressor and the second compressor and modifying the speed of the first compressor and the second compressor according to the combined COP optimization.

7. The method of claim 6 , further comprising operating the cooling system in the first refrigerant loop only mode;

determining if additional cooling is needed for at least one of the cabin and the battery;

determining a maximum speed of the first compressor; and

adjusting the speed of the first compressor up to the maximum speed of the first compressor to satisfy the cabin cooling needs and the battery cooling needs.

8. The method of claim 7 , wherein the maximum speed of the first compressor is determined based on a speed of a blower and a speed of said vehicle.

9. The method of claim 7 , further comprising determining an absolute limit for the speed of the first compressor.

10. The method of claim 9 , wherein the absolute limit is determined based on at least one of a predetermined limit, a head pressure limit, and a voltage limit.

11. The method of claim 9 , further comprising increasing the maximum speed of the first compressor up to the absolute limit.

12. The method of claim 11 , further comprising providing a coolant temperature sensor; and

receiving a coolant temperature reading from the coolant temperature sensor; and

increasing the maximum speed of the first compressor based on the received coolant temperature reading.

13. The method of claim 9 , further comprising determining a cooling capability of the first refrigerant loop with the first compressor operating at the absolute limit;

determining a combined cooling need of the cabin and the battery;

comparing the cooling capability of the first refrigerant loop with the combined cooling need; and

operating the cooling system in the dual refrigerant loop mode when the combined cooling need exceeds the cooling capability of the first refrigerant loop.

14. A method of operating a cooling system for a vehicle comprising:

providing the cooling system including a coolant loop configured to exchange heat with a battery; a first refrigerant loop comprising a first compressor, an evaporator configured to exchange heat with a cabin of said vehicle, and a first chiller configured to exchange heat with the coolant loop; and a second refrigerant loop comprising a second compressor and a second chiller configured to exchange heat with the coolant loop, wherein the coolant loop comprises a coolant valve for selectively directing or preventing the flow of a coolant between the battery and each of the first chiller and the second chiller;

providing a cooling system controller operably coupled to the first compressor, the second compressor, and the coolant valve;

determining cabin cooling needs and battery cooling needs;

operating the cooling system in a dual refrigerant loop mode;

modifying a speed of at least one of the first compressor and the second compressor to satisfy the cabin cooling needs and the battery cooling needs;

determining if additional cooling is needed for at least one of the cabin and the battery; and

determining if the additional cooling is for a cabin cooling request or for a battery cooling request;

determining the speed of the second compressor corresponding to an optimal coefficient of performance (COP);

determining if the second compressor is operating at or above the speed corresponding to the optimal COP; and

adjusting the speed of the second compressor up to the speed corresponding to the optimal COP when the additional cooling is for a battery cooling request and the second compressor is operating below the speed corresponding to the optimal COP.

15. The method of claim 14 , further comprising adjusting the speed of the first compressor to satisfy the cabin cooling needs when the additional cooling is for a cabin cooling request.

16. The method of claim 14 , further comprising determining the speed of the second compressor corresponding to an optimal coefficient of performance (COP);

determining if the second compressor is operating at or above the speed corresponding to the optimal COP;

determining a combined COP optimization for the first compressor and the second compressor; and

adjusting the speed of the first compressor and the second compressor according to the combined COP optimization when the additional cooling is for a battery cooling request and the second compressor is operating at or above the speed corresponding to the optimal COP.