Research On 3kW DC/DC Converter

With the development of power semiconductors,power converter has been widely used in industry.In order to meet the need of enterprise,this paper develops a 3kW 28VDC/±135VDC converter.This paper firstly introduces the research background of the subject,and explains the reasons for selecting the ZVS phase-shifted full-bridge circuit and the primary-side peak current control of the transformer.Then it analyzes the working priciples of ZVS phase-shifted full-bridge PWM converter and the importance of the slope compensation in peak current control,which will provide the theoretical basis for main circuit design.In order to correctly reflect the DC bias of primary current of transformer,this paper proposes a dual magnetic ring current detection circuit.This circuit can effectively reflect the DC bias of primary current of transformer by using the nonlinear characteristics of the magnetic ring.This paper also gives the design steps and attentions of this current detection circuit.Then in this paper,based on the small signal model of Buck converter,the small signal model of ZVS phase-shifted full-bridge is obtained by using small signal disturbance method,through which the small-signal model of phase-shifted full-bridge converter under peak current control is established,which is convenient to design compensation part in close-loop control.At the same time,this paper gives the design process of main circuit and control circuit,such as the selection of components in the main circuit,the design of transformer and filter inductor,the analysis of RC absorption circuit and the design of softstart and driver circuit in order to meet the converter needs.Based on the above theoretical analysis and engineering design,a 3kW prototype is developed.In the end,the correctness of theoretical analysis and engineering design is verified by simulations and experiments.Especially for the DC bias of transformer,the experimental results show that the DC bias of transformer can be effectively suppressed by the dual magnetic ring peak current detection.