Application of ptc heater for electric vehicle
Electric vehicles have a long history and have been around for as long as internal combustion engine vehicles. Due to the limitations of the battery and other factors in the early electric vehicles, the design idea of the air conditioning system is not to consume electric energy during use. One method is to provide heating in the car while charging the battery, which is only suitable for short-distance driving. That is, when the electric vehicle starts to operate, the interior of the vehicle can maintain a comfortable temperature, and as the operating time increases, the performance of the air conditioning system decreases rapidly. Another method is to use an independent small-scale fuel device to increase the ambient temperature in the electric vehicle compartment. Although this method can better meet the heating requirements in the compartment, the combustion products will still pollute the environment. With the continuous advancement of science and technology, there are more and more methods for indoor heating of electric vehicles, such as the use of PTC heaters, air-conditioned seats, heat pump air-conditioning systems and other methods.
1. Use PTC heaters for heating PTC generally refers to semiconductor materials or components with a large positive temperature coefficient, and usually refers to a positive temperature coefficient thermistor. When the temperature of the PTC thermistor exceeds the Curie temperature, its resistance value will increase sharply, so that the power of the heater becomes very small. At present, when the ambient temperature is low, most electric vehicles use heaters made of PTC thermistors to increase the ambient temperature inside the vehicle. When the heater made of PTC thermistor is used to heat the interior of the electric vehicle, although it has the advantages of constant temperature heating, no open flame, fast temperature rise, low cost, long service life, green environmental protection, and no need for a control system, it does not need a control system. The shell of the heater assembly needs to be changed, but the energy consumption is high. When the interior of the car needs to meet the requirements of relevant laws and regulations such as defrosting and heating, the PTC needs to reach a power of more than 3kW. This will not only have a greater impact on the battery, but also produce peculiar smell and pose a safety hazard. Since the PTC heater is a heating device that directly converts electrical energy into heat energy, its maximum energy efficiency ratio is only 1. For electric vehicles, PTC heaters are not an ideal heating solution.
2. Use the waste heat of the motor coolant, and at the same time assist the PTC heater for heating. During the driving of electric vehicles, the driving motor needs to be cooled, so a heating method similar to that of traditional internal combustion engine vehicles can be used, that is, use the waste heat of the motor coolant to improve Ambient temperature inside the vehicle. When the residual heat of the coolant cannot meet the heating requirements of the vehicle interior, a PTC heater is used for heating. It can be seen from this that when using this method to supply heat to the interior of the electric vehicle, almost no electric energy is consumed when the PTC heater is not working, but some pipelines, valves, heaters and other components need to be added. The control system was redesigned.
