Current-fed Soft-switching Highvoltage Power Supply

High voltage power supply plays an important role in many applications. This dissertation is to design a high voltage supply, whose properties are high step-up ratio and high reliability. The main circuit topology analysis, power topological parameter design, soft-switching condition analysis, small signal model establishment, control circuit design and system software programming must be studied in depth to accomplish these specifications.The current-fed full bridge circuit is chosen as the main converter topology. It is a combination of boost circuit and full bridge circuit. The circuit meets the requirements, such as small ripple of input current, high step-up ratio and high efficiency and so on. The active clamp limits the voltage overshoot when the switches turn off. So the converter devices are protected. This thesis researches the principle of current-fed full bridge converter, then according to the state of the converter, calculates the parameter values of the main power topology.The converter can achieve soft-switching through the resonance between the capacitance and the transformer leakage inductance. Then the soft-switching conditions are analyzed. The optimization design of active clamp capacitor is also given. And the converter is simulated by Saber, to verify the correctness of the theory. The current-fed full bridge model has been made by small signal method. In order to make the converter works with stable performance and good dynamic response, the dual-loop control strategy of the current-fed full bridge is analyzed and studied in detail. Then the simulation verifies the stability and dynamic characteristics of the converter with PI compensators.Auxiliary circuits are the integral part of the converter. The soft-start circuit, sampling circuits and driver circuits are designed. Then the current-fed full bridge experiment is performed, and the converter performance must meet the design requirements.The simulation design and topology experiments in the dissertation have verified the feasibility of high output voltage by the current-fed full bridge converter. And the high efficiency and high reliability of the converter are also achieved.