The Design Of The Air Condition System Of Electrical Bus

Electric vehicle is a new industry,the development of electric vehicle can relieve the pressure of the shortage of energy.More and more pow electronic devices is used on electric vehicle,it can enhance the level of electronization.But it also bring a new problem,a complex electromagnetic environment,than a traditional vehicle.The electromagnetic interference affects the stability of the electronic equipment on electric vehicle.For a comfortable travel condition and the stable operation of air-condition,it has to study the electromagnetic interference of the electric vehicle and think about these factors when we design the circuit of air-condition.It is important that improves the ability of anti-interference of air-condition.This thesis describes the improvement of air-condition controllers(A/C-ECU)and Panels which are used on electric bus.The project makes the system adapt the electromagnetic environment on electric bus.At first,this thesis analyzes the old design and the source and type of the electromagnetic interference(EMI).Then,it ensures what kind of EMI damage the operation of air-condition.Something measures are used to improve the anti-interference performance.At last,the air-condition system will be ensured,it bases on PIC chips.Because a A/C-ECU keeps a certain distance from a panel,it becomes urgent that chooses a appropriate communication mode to protect the operation of system.Two kinds of communication,current loop communication(CLC)and CAN Bus,are discussed in the thesis.In point to point communication,CLC is adopted.If a panel wants to control two or more A/C ECUs,CAN BUS is adopted.In current loop,a protocol called Modbus is used.SAE-J1939 protocol is adopted in CAN Bus.This article design relevant circuit which use optical couples to isolate signal.A stable air-condition is not only decided by communication but also depend on the correctness of AD values.Only correct AD values can guarantee that air-condition system run normally.But the complicated electromagnetic environment on bus may lead to get wrong AD value.So we must take effective measures to obtain right AD values.On the one hand we should enhance the design of anti-interference about hardware circuit,on the other hand we also improve the filter in software.