New energy vehicle PTC heater PTC technology and market
Compared with the ancient automobile thermal management system, the difference between the new energy automobile thermal management system is that the management tool is extended from the cockpit to the battery, motor and electronic control platform, and the second is that its function is extended from simple cooling to heat preservation and heating. . Therefore, compared with ancient cars, the new energy vehicle heat management system has newly added electronic water pumps, electric compressors, electronic stretch valves or four-way valves, cooling plates, and heating systems (heat pumps or PTC systems).
New energy vehicle air conditioning system plan
The heating source of the air-conditioning system of a fuel vehicle is mainly supplied by the engine coolant, while the heating system of an electric vehicle is different from it. The most common heating plan for electric vehicle air-conditioning systems is as follows:
① Heat pump. The working principle of the heat pump air-conditioning system of an electric vehicle driven by a transmission belt with a brushless DC electric idea is shown in the figure. The cooling/heating mode of the air-conditioning system is switched by a four-way reversing valve. The solid arrow shows the cooling condition, and the dotted arrow shows the heating condition. In principle, the system is no different from ordinary heat pump air conditioners, but for electric vehicles, it has specially developed a dual-working cavity sliding vane compressor, a DC brushless electric idea and an inverter control system. Under heat pump conditions, when the system switches from defrosting mode to heating mode, the condensed water on the heat exchanger in the air duct will quickly evaporate, forming frost on the windshield, which affects driving safety.
②ptc electric heater. PTC electric heater is a kind of heater that uses PTC thermistor element as the source of fever. PTC thermistors are made of semiconductor materials from time to time. Its resistance changes sharply with the change of humidity. When the outside temperature drops, the PTC resistance value will decrease, and the fever will increase in response. According to the material, it can be divided into ceramic PTC thermistor and organic polymer PTC thermistor. The ceramic PTC thermistor is used for the auxiliary electric heater of the air conditioner. The PTC thermistor element has the characteristics of changing the temperature according to the situation, and its resistance value increases or decreases accordingly. Therefore, PTC heating has the characteristics of energy saving, constant temperature, safety and long service life.
Air conditioning auxiliary electric heaters can be divided into bonded ceramic PTC heaters and metal PTC tubular heaters. The bonded ceramic PTC heater is a heater that bonds multiple ceramic PTC chips and aluminum corrugated heat sinks with high temperature resistant resin glue. It has good heat dissipation and stable electrical functions. Among them, the bonded ceramic PTC heater is divided into the heater surface charged type and the heater surface uncharged type.
The metal PTC tubular heater uses imported nickel-iron alloy wire as the fever material, and the fever tube is inlaid with aluminum heat sink, which has a very good heat dissipation effect. The heater is equipped with a temperature controller and thermal fuse to make the product safer and more reliable. This kind of heating has the good characteristics of PTC material, and some air conditioners use this kind of heater as auxiliary heating.
③Waste heat + auxiliary PTC. Use the heat generated when high-power devices (power changes, drive motors, motor controllers, etc.) work to exchange heat for the conditions in the car. When the heat is insufficient, the auxiliary PTC heater is activated.
The energy consumption of new energy vehicle air-conditioning accounts for more than 15% of the energy consumption of the whole vehicle; the PTC thermal resistance heating heating method consumes a lot of energy, and the heat pump technology has obvious energy-saving effects, which has become the trend of replacing PTC. International BMW, Mitsubishi, and Nissan first adopted the technology of electric scroll compressors. At present, there are also partial models adopted in China, but the current level of technology may be at the level of stand-alone.
Regarding heat pump technology, further improving power density and lowering the very low operating temperature are the focus of the next step of research and development, as well as energy-saving methods.
