The working principle of the new energy vehicle system is the same as that of the traditional fuel powered vehicle air conditioning system, but the driving method of the air conditioning and the generation method of warm air are different. New energy vehicles use high-pressure electric air conditioning compressors, driven by power batteries. Warm air is usually heated by two methods: one is through heating and then circulating to provide heat to the warm water tank, and the other is by directly heating the air passing through the evaporation box to achieve warm air.
The electric compressor of the air conditioning system for new energy vehicles is driven by high voltage electricity. The electric air conditioning compressor compresses the low-pressure and low-temperature steam from the evaporator and pressurizes it into high-pressure and high-temperature steam to circulate around the system.
Pure electric vehicles do not have traditional car engines or heat sources, so they need to rely on the thermal energy of PTC for heating. PTC stands for Positive Temperature Coefficient.
The PTC heater adopts PTCR thermosensitive ceramic components, which are composed of several single pieces combined and bonded with corrugated heat dissipation aluminum strips through high-temperature bonding. It has significant advantages such as low thermal resistance and high heat transfer efficiency.
2. The air conditioning system of the BMW 530Le (F18 PHEV) plug-in hybrid model
The BMW 530Le (F18 PHEV) plug-in hybrid model uses an electric refrigeration compressor. Due to the refrigeration compressor having an electric drive device, it can independently drive the air conditioner from the engine.
In order to cool the coolant circulating in the high-pressure power battery unit, a cooling device was used. The refrigerant circulation of the cooling high-pressure power battery unit is connected in parallel with the refrigerant circulation inside the cooling vehicle. The air conditioning refrigerant cycle and the high-pressure power battery unit coolant cycle are connected to a coolant refrigerant thermal connection.
The electric air conditioning compressor of the BMW 530Le (F18 PHEV) plug-in hybrid model is a spiral compressor (also known as a vortex compressor), with an electrical power of approximately 5 kW. The driving voltage of the electric compressor is within the range of 288V~400V. If the voltage is above or below this range, it will reduce power or disconnect.
The heating heat exchanger of the BMW 530Le (F18 PHEV) plug-in hybrid model is integrated into the coolant circulation of the engine and motor. Due to the particularity of hybrid vehicles, the engine is unable to circulate and heat the coolant to the necessary temperature while driving. Therefore, the air conditioning and heating system is also equipped with an electric heater.
Installation location of heating system components.
The function of an electric heating device is the same as that of a through type heater in principle. An independent heating circuit can be established through a switching valve, and the circulation of the circuit is maintained by an electric coolant pump.
When the coolant temperature is low, such as shortly after departure or in pure electric driving mode, the electric switching valve is controlled through the junction box electronic device. The electric switching valve prevents the inflow of engine coolant circulation. Now, the electric coolant pump draws the coolant into the electric heating device and heats it, and delivers the coolant to the warm air heat exchanger as needed through a dual water valve.
When the coolant temperature is high, the coolant heated by the engine flows through the conversion valve, electric heating device, and double water valve that are opened without electricity, and reaches the heating heat exchanger. The coolant discharges a portion of the heat here to the air flowing through the heating heat exchanger, and finally flows back into the generator coolant circulation. The electric heating device is now turned off, but the electric coolant pump is activated.