Design Of Charger For Low-speed Electric Vehicle

The energy consumption and exhaust emissions of traditional automobile has caused a serious impact on the environment, haze is a particularly evident. To improve the environment, we must change the energy structure and inhibit the rapid growth of the number of motor vehicles. In recent years, with the introduction of the concept of a low-carbon economy, the electric car industry continues to grow, so the development of charger becomes crucial.This paper combining the design specifications of charger, based on the charging characteristics of lead-acid batteries, then design the car charger which can monitoring the battery state of charge in time and recorded it. Car charger as a power electronic device is directly connected to the grid. Therefore, it has a higher demand in the harmonic processing, power factor, efficiency and so on. It is very important to select the appropriate topology and control it.This paper based on the analysis of the existing topology and control theory, Designing a car charger of 3kW and mainly to complete the following principles of design, production and commissioning work:According to the design requirements of the charging machine, selected power factor correction circuit which has Boost topology as a pre-stage input for charger, designed the filter circuit of into the line side to suppress electromagnetic interference.On the basis of the principles of design PFC rectifier,the paper produced a model for debugging, the output voltage has small ripples and meet the requirements. After class link of buck use a full-bridge circuit which has soft switch-mode, in order to meet the efficiency requirements.In this paper, we analyze in detail the calculation of the parameters about the power conversion circuits and select devices,also relates to the control loop.The central control unit use the P89LPC938 microcontroller that producted by Philips company, designed the battery voltage, current, temperature sampling circuit to achieve intelligent control and safety of charger. The paper verify the correctness of the theory combined by debugging and simulation.Metaphase of the experiments the paper using the prototype debug and PSIM simulation verify the correctness of the theoretical stage, Later stage make charging prototype and obtain the experiment result.Experiments show the feasibility of the theory, the results meet the charging power factor, ripple, efficiency and other requirements.