Control Strategy Research And Implementation Of ZVS Half-bridge Three-level Charger

With the prosperity of the world economy, renewable energy crisis intensified. It is a common research topic for countries to make use of natural resources rationally, promote green energy development. Therefore, the development of electric vehicles is becoming a trend in the automobile industry, the charging system requirements are also getting higher and higher. The DC/DC converter is an important part of charging system, therefore, the research of DC/DC converter is very important. The research is based on the half-bridge three-level converter topology in this paper, then design the switch control strategy to make switches achieve ZVS(Zero Voltage Switch), and design a charge control system which has a good steady state and dynamic.Firstly, according to the working principle of the half-bridge three-level converter, then analyze these control methods. According to different soft switching modes, divide converter into zero voltage switch converter and zero voltage zero current switch converter. By comparing the different type of switching device, this paper choose ZVS converter to research. And the paper compared and analyzed two common control methods, then chose limited bipolar control mode to achieve zero voltage switch. Analyze switch modes of converter on the basis of this control, verify that the theory is correct, it can achieve ZVS. And research the related questions of the realization process, through building a model on Simulink platform to prove that this control method can achieve ZVS.Then use state space averaging method to build the small signal model of half-bridge converter. Then research the charge control strategy, according to the shortcoming of voltage single loop control strategy leads to improved control strategy. And design the controllers of voltage double loop control, compare and analysis uncompensated and compensated control system performance. Do simulation experiment for these two control strategies, then compare and analyze their simulation results.Finally, the system software is designed, then it is applied to half-bridge three-level converter to test. Through experiment can verify the correctness of the system software designation. At the same time, it verifies the limited bipolar control strategy which is studied in this paper can achieve zero voltage switch; according to test waveforms and test data can reflect that output voltage ripple, regulation accuracy and conversion efficiency all achieve the design requirements. So the research and design in this paper can achieve the design requirements.