Application of temperature control switch in PTC heating of pure electric vehicle

Now electric vehicles cancel the traditional engine, and new development of the whole vehicle PTC heating system, in order to achieve the cab, cabin heating and vehicle defrosting, defogging demand.  During the operation of PTC heater, if abnormal operation occurs, the PTC heater and vehicle components will be damaged at least, and the car will spontaneously ignite at most.  Therefore, electric vehicles have high requirements for the safety of PTC heaters, and many manufacturers choose temperature control switches as a layer of protection in order to improve the safety of heaters.  

The existing PTC heater generally adopts the series temperature control switch in the low-voltage control loop. When the temperature reaches the preset temperature, the normally closed contact of the temperature control switch is disconnected, then the low-voltage loop is disconnected, and then the high-voltage output loop is disconnected.  We are worried that the safety of a single temperature control switch is too low, so it is made into double protection, which is to add two temperature control switches in the circuit.  The electric vehicle PTC heater dual protection device includes power battery, high voltage distribution unit, control module and PTC heating module. The PTC heating module is connected with the control module signal through the loop, and the PTC heating module is connected with the power battery through the high voltage distribution unit.  PTC heating module contains a temperature control switch, a temperature control switch through the low-voltage control loop, connected in series between the control module and the heater power control module, and then connected to the 12V low-voltage power supply;  The temperature of the temperature control switch is set to open at 85±5°C and close at 60±15°C. The second temperature control switch is connected between the control module and the base iron through the low-voltage control loop 2.  The two ends of the heating component are respectively connected with the two high voltage power supply ends of the high voltage distribution unit. Through the two temperature control switches in series in the loop, the dual protection of the PTC heater is realized.  When the first temperature switch fails, the PTC heater is abnormal and continues to work. When the temperature protected by the second temperature switch is reached, the PTC is protected again.

The dual protection temperature control switch can effectively avoid accidents caused by the failure of the temperature control switch of the PTC heater, so as to effectively protect the service life of the PTC heater and vehicle components, and avoid the safety accidents caused by excessive heating, such as auto spontaneous combustion.