The heat pump is an application that is responsible for both the heating and cooling of the cabin, per Figure 2-3. The method is similar to the aforementioned cooling circuit with a compressor, condenser, expansion valve, and evaporator. However, this can be used in both directions, with either the radiator being used as evaporator to warm in the cabin, or the radiator being used as condenser to cool the cabin. However, the smaller the differential of the ambient temperature and the refringent temperature is, the less efficient the heat pump system will be. So, the higher differential between the ambient environment and refrigerant temperatures, the more efficient the system will be.

In order to improve the CoP of a heat pump system, additional heat sources (for example, traction inverter, compressor motor, blower motor, and so forth) can be added into the system, as shown in Figure 2-4. This increased (CoP) would help increase the vehicle’s driving range. However, this approach does have its drawbacks, as well. It adds more complexity due to the additional circuitry and connectivity required. It is also heavier as more tubing, refrigerant and/or coolant would be needed.

Lastly, an EV thermal management method that can be used today is combining the Heat pump and PTC heater systems. This can be used in cases where there is not enough available heat to be captured from outside the vehicle due to cold climate, nor is there sufficient heat from other heat sources. This method helps ensure the end-user stays warm, but it requires a heavier, more complex and more expensive design