Hello, as the power source of the car, the power battery of new energy vehicles will generate heat during charging and discharging. The performance of power batteries is closely related to battery temperature.
In order to extend the service life of the power battery as much as possible and obtain maximum power, the battery needs to be used within the specified temperature range. In principle, the power battery unit is in an operable state within the range of -40°C to +55°C (actual battery temperature). Therefore, current new energy power battery units are equipped with cooling devices.
Power battery cooling systems include air-conditioning circulation cooling, water-cooling and air-cooling. 1. Air conditioning circulation cooling type
In high-end electric vehicles, there is a refrigerant circulation loop inside the power battery that is connected to the air conditioning system. The power battery cooling system of plug-in hybrid vehicles is shown in the figure below.
The power battery unit is directly cooled by coolant, and the coolant circulation loop and the refrigerant circulation loop are connected through a coolant-refrigerant heat exchanger (ie, cooling unit). Therefore, the refrigerant circulation circuit of the air conditioning system consists of two parallel branches. One is used to cool the interior space of the vehicle, and the other is used to cool the power battery unit. Each of the two branches has an expansion and shut-off combination valve. The diagram of the two independent cooling systems is as shown in the figure below. Cooling working principle:
The electric coolant pump delivers coolant through the coolant circulation loop. As long as the temperature of the coolant is lower than that of the battery module, the battery module can be cooled using only the circulating flow of the coolant. The coolant temperature rises and is insufficient to keep the battery module temperature within the expected range.
Therefore, the temperature of the coolant must be lowered, and a coolant-refrigerant heat exchanger (i.e. cooling unit) is required. This is the interface between the power battery coolant circulation loop and the air conditioning system refrigerant circulation loop.
If the combined expansion and shutoff valve on the cooling unit is electrically activated and opened, liquid refrigerant will flow into the cooling unit and evaporate. This absorbs heat from the ambient air and is therefore a coolant flowing through the coolant circuit. The electric air conditioning compressor compresses the refrigerant again and delivers it to the capacitor, where it becomes a liquid again. The refrigerant can therefore absorb heat again. In order to ensure that the coolant channels dissipate heat from the battery module, the entire surface of the cooling channel must be pressed against the battery module with an evenly distributed force. This pressing force is generated by spring bars embedded in the coolant channels. The spring bars are adapted to the battery module geometry and the lower housing half.
Hope this helps!