Research And Design On Digital Controlled Phase Shifting Full-bridge Soft Switching ZVS Power Converter

With the increasing development of global traditional motor vehicles, environmental pollution caused by vehicle exhausting is more and more serious, so people are paying more and more attention on it. In addition, the price is rising and reserves is dwindling about oil.These have contributed to the transformation of the automotive industry from the traditional industry to the new energy automotive industry. As an impotant part of the new energy vehicle, the on-board DC/DC converter is constanly concerned. In order to avoid the waste of electric energy and increase the pure electric vehicle battery life, people have an increasing demand for new on-bord DC/DC converter with high efficiency, small volume, light weight, superior safety performance. In order to improve the efficiency of vehicle’s DC/DC power supply, this paper chooses phase shifting full-bridge DC/DC converter as the main circuit topology and TI DSP 2812 as main controllerchip to design a full digital phase shifting full-bridge DC/DC converter for vechicle power supply.Fistly, this paper makes a thorough study on the PS-FB-ZVS DC-DC converter. We make a detailed analysis at its 12 working process, and then conclude a few key issues that can affect phase shifted full-bridge to achieve ZVS. Then, this paper makes reseach on these key issues. PS-FB-ZVS DC-DC converter is a kind of excellent performance of DC/DC converter. Its two leading bridge arms are easiser to achive zero voltage switching and the lag bridge arms can also achieve ZVS under some certain conditions. So it has less swithing loss, thereby reducing the difficulty of heat dissipation design and EMC design. This complies with on-board DC/DC converter miniaturization and safety requirements.Secondly, this paper mainly completes the PS-FB-ZVS DC/DC converter main circuit research and design, and then completes the simulation of main circuit through the simulation software Saber. The simulation’s results verify the correctness of this design. At the same time, this paper completes the establishment of the small signal model of mian circuit through the analysis of the modeling of main circuit. Based on small signal model analysis, this paper completes the design of double closed loop controller whose inner ring is load current loop and outer ring is output voltage loop. Under the environment of MATLAB simulation, the results of simulation prove that the design of the controller has good dynamic performance and steady-state performance.Then, this paper designs the control system of PS-FB-ZVS DC/DC converter including hardware design and software design. The hardware design mainly includes the peripheral cicuit design of TMS320F2812, signal acquisition circuit, driving circuit and protecting circuit design.Software design mainly includes the soft start program design, the pahse shifting PWM design, incremental PID program design and various protection design and so on.Finally, this paper completed the full digital phase shifting full-bridge DC/DC converter of the experiment test,and completed the output voltage 14 V, output current 150 A and the maximum output power 2.5KW’s test prototype. Then we completed the debugging of experimental prototype and the test prototype development work.