The Design And Realization Of Charging System For Electric Vehicle

With the shortage of sources and more worsening air pollution, we pay more attention about the researching of EV( electric vehicle) a new means of transportation, we use more and more Nickel hydride(Ni-MH) battery in EV, because of it 's no remember effect, good performance in overcharge or discharge. The process of batteries charge and discharge Influent the reliability of the system. So design a reliably charging system is important for EV. In order to make EV charger have good performance, we must to find the best charging model. At the same time, the intelligent charger basic on MCU have the merits such as its circuit is simple,reliable, parameter adjustment is convenience, charging time is short, consumption is low, and also the fault of use it is low. All of those are great significance for charging system's design and development.How to choose the method of charging process and how to control the charging process, improve the efficiency, and ensure the process rapidly and safety is the content of this paper. The study of this paper includes the following aspects:The method of charging process have great impact on the performance and life for batteries , in the study of Ni-MH battery charge and discharge principle, common characteristics and the current charging methods and end-of-charge control methods, the three-stage charging method (constant current, constant voltage, the trickle current) and the integrated control method (temperature control, timing control, maximum voltage control, incremental negative voltage control) have been used in our system.In the area of charging system research include charging circuit and charging control strategy research. Because the power of output is high, so we use full-bridge phase-shifting soft-switching circuit, and selected MOSFET as switching devices, design the drive circuit of switching devices and magnetic components. Completed calculate and select the resonant devices of the circuit. Implementation of the soft-switching circuit, to reduce the switching loss and circuit noise. Design the auxiliary control circuit based on PIC16F877MCU and UCC3895. Monitor the battery temperature, voltage and current to change the status of its work. Protection circuit, auxiliary power supply circuit guarantee the completion of the entire charging circuit functions can be achieved.Finally, the relevant system software design was introduced. Realize the purpose of through software to improve charging control, ensure the safety of our charging circuit.