Research On PS-FB Based Adjustable DC Power

Regulative DC power is a convenient equipment for power conversion used in various fields need to be supplied with stable or variable DC power, including medical treatment, instrumentation, automated production line testing and inspection. With the development of power and electronics, the requirements for control performance of electrical equipment are increasing. And so is regulative DC power. An adjustable compound DC-DC power based on full-bridge phase-shift ZVZCS converter is proposed.Compound regulative DC-DC converter is composed with a switching converter and a linear regulator. The first class is switching converters, which regulate and stabilize DC voltage once. The first class is linear regulators, which give output with high precision. Therefore, the compound regulative DC-DC converter has the advantages of both linear power and switching power. Switching converter is with high power density, small size, light weight, can achieve higher power conversion. Moreover, the voltage drop of the linear regulators could be limited, and the linear power loss and the nonlinear variation of parameters caused by the rise of temperature is reduced. The regulation accuracy and output stability are further improved.PS-FB-ZVZCS converter is an excellent switching converter that can provide soft switch for two bridges arm within a wide power range. Because of the simple structure, being easy to control, and small switching losses, PS-FB-ZVZCS converter has been widely used in the fields of high power DC / DC transformation. A 50V/20A PS-FB-ZVZCS is designed first and the key issues in the applications of regulative power with whole range are analyzed later. To the loss of secondary side duty cycle, simulation and analysis is carried out, improvement strategy is proposed at last. Experiments show that the strategy is practical and effective.Dynamic characteristics of the power converter are closely related to control system. To the characteristics of compound regulative DC-DC converter, modeling and control system design of PS-FB-ZVZCS converter is proposed emphasisly in this paper. Its equivalent BUCK converter is analyzed and small signal model obtains;the characteristics of the PID control and one-cycle control (OCC) are compared and analyzed and a digital control system is proposed. In this control system, the PID one-cycle control (PID-OCC) technology is used in PS-FB-ZVZCS converter. Digital simulation is carried out by MATLAB. PID-OCC control method is proved to be with quick dynamic responses and high regulation accuracy, and be very suitable for the control system of PS-FB-ZVZCS converter.Based on the analysis of the performance of linear regulator, the control process and key issues in the compound DC converter are discussed, and a feasibility analysis is conducted. Theoretical study and experimental demonstration shows that DC-DC power based on PS-FB-ZVZCS converter improves the precision of high-power, dynamic response and other dynamic features, while power density is also improved.