Realization Of The Charging Pile Based On Phase Shifted Full Bridge Circuit

Nowadays, energy shortage and environmental pollution are serious problems. Especially in recent years the global hazy weather increases, further showing the environmental problems to the extent that they need to be addressed. In fact, the exhaust emission of motor vehicles is the main one of the pollutants. We must try to use clean energy instead of the traditional gasoline and diesel. As a result electric vehicles that have zero emission and no pollution become the focus of global attention and how to realize high-efficient and fast charging for electric vehicles has become a research focus in the industry.Through circuit topologies commonly used in power electronic system, we can find that the phase shifted full bridge DC-DC converter is suitable for high power and it can achieve soft switching. Due to high efficiency, the topology is a good choice for electric vehicles. Based on phase shifted full bridge converter, a charging pile is proposed in this paper which has an output current waveform that is the superposition of an constant current compoment and an alternating current compoment. In theory, this waveform can reduce ac impedance and then improve the charging efficiency for the battery.Firstly, this paper introduces present development status of electric vehicles and charging piles, battery charging methods and the application of soft-switching technology. And then around the characteristics of this converter, this paper describes the basic principle of phase-shift full bridge circuit topology and some related waveforms, also analyzes the critical issues existing in the topology, such as the duty cycle loss, the voltage oscillation in the secondary side of transformer and soft-switching conditions for lagging arm. Especially for the second issue mentioned above, this paper gives a formula to calculate parameters of these components used in the absorption circuit.Second, this paper designs the hardware circuit and software control of charging pile. Hardware design mainly includes the selection of power device in the main circuit, the design of magnetic components, the design of the auxiliary power supply, the design of sampling circuits and the design of drive circuit. At the same time, this paper finishs the model of phase shifted full bridge converter based on the small signal model of Buck and State-Space Averaging Method. And then on the basis of this model, this paper use thecontrol kit called SISO in Matlab software to complete the double closed-loop control system which has an inner current loop and an outer voltage loop. Later, this paper build the digital control platform with the DSP chip TMS320F28027 as the core, and implement the function including phase shifted control, PI regulator, soft starting, overvoltage protection, overcurrent protection and double-closed loop control.Finally, the paper uses the simulation software called PSIM to finish the open loop and closed loop simulation for the charging pile respectively, also gives the simulation waveforms. At the same time, a 3k W prototype converter is made and the experiment results are analyzed which verify the correctness of the design.Based on phase shifted full bridge DC- DC converter and DSP digital control platform, the charging pile whose output current are the superposition of DC component and AC component is achieved. The implement not only lay a foundation for the next step to determine the optimal values of the amplitude and frequency of sine waveform, but also provide a train of thought and direction of charging piles with larger power, in a sense promoting the development of charging pile.