Phase-Shift Full-Bridge Portable Charging Power Supply For Electric Vehicles

Currently, our country is facing increasingly serious environmental pollution and energy crisis brought by the rapid development of the automobile, Electric Vehicles become an important way to solve the two problems. However, the performance improvement of the energy storage batteries can't match the development speed of Electric Vehicles, and the location of the charging station is fixed and they are inconvenient to be used. So it is necessary to develop a low-cost, flexible portable charging power supply, resupplying energy anywhere and anytime, to lay the foundation for a wide range of applications of the charging technology.The poor working conditions of the vehicles require that the charger must have a seal structure to block dust and some other things, so there is only one way to dissipate heat with natural cooling. Therefore, high efficiency becomes its most important technical features, and it should bring low harmonic pollution to the grid, with the characteristics of light weight, small size, high reliability, against mechanical shock and vibration.With the combination of the technical indicators and protection grade of the portable charger for Electric Vehicles, the overall scheme of charging power supply is determined with two circuits of the anterior active power factor correction circuit and the lag DC/DC converter. The specific forms of implementation of the two circuits are analyzed. On the one hand, the principle and necessity of the active power factor correction circuit are analyzed. By comparing the advantages and disadvantages of the different circuit topology and control methods which can achieve active power factor correction, the single-stage boost circuit topology and the corresponding average current control mode suitable for this system are selected. One the other hand, in order to get high efficiency of the charging power supply in a wide load range, the phase-shift full-bridge PWM converter is selected to accomplish the lag DC/DC converter. A variety of improved circuits of phase-shift full-bridge zero voltage switching PWM converters are listed. By comparing the advantages, disadvantages and the degree of difficulty to be achieved, the improved PWM converter added by two clamping diodes and one resonant inductor as the final solution is chose. The working principle of the improved converter is analyzed detailed, the functions of the added auxiliary part are discussed. The different conditions to achieve zero voltage switching for the forward and lag legs and the factors to cause secondary duty cycle loss are given.With the solutions and technical specifications of the charging power supply, the specific parameters of the main circuits and control circuits of the two circuits are designed separately. With the use of Saber and PSPICE simulation software, the simulation analysis and parameter optimization are carried out respectively. A 2.4kW charging power supply prototype for Electric Vehicle is developed, which is tested at different load conditions. The results show that, the charging power supply has high efficiency, high reliability and low harmonic pollution.