Design And Implementation Of 1.4kW Digital Switching Power Supply System

With the rapid development of digital control strategy and modern power electronics technology,the digital realization of switching power supply has gradually become a hot spot of modern power supply technology.In this paper,the switching power supply,which is composed of the front stage interleaved Boost PFC and the post stage phase-shifted full bridge DC/DC topology,is selected as the research object.In order to implement the combination of Boost PFC and DC/DC in digital control system to improve the stability reliability and intelligence based on the UCD3138 digital power control chip,some studies have been done as follows:Firstly,operational principles of interleaved Boost PFC and phase-shifted full bridge DC/DC are fully analyzed,and small signal mathematical models of the front stage and post stage converters are established,and the corresponding transfer function are obtained.The average current method based on digital chip control is selected,and the corresponding control strategy is given for the current imbalance of the two-phase branch of the front stage converter.The loss of duty ratio cycle on the post stage and the implementation of soft switching technology are analyzed,and corresponding control strategies are proposed.Secondly,according to the digital switching power supply design requirements and circuit operating characteristics,the main circuit and auxiliary circuit of the main device parameters were determined.The digital controller with front and rear stages are designed.Combined with the small signal model of the converter,the open-loop Bode graph is drawn by Matlab tool to verify the result of theoretical analysis.Through further simulation analysis,the system control strategy is verified and the conclusion is reached.Finally,a full digital switching power supply of 1.4k W and the front stage and post stage are controled by the digital power chip UCD3138.Based onLabview visual interface,the input and output status monitoring,fault monitoring and alarm,zero sleep and wake control are realized,which makes the control of switching power supply more concise and efficient.The result of the experiment shows that the current ripple of the front stage converter was controled within a reasonable range,the power factor of the supply complys with the design requirements,the soft-switching technology of the post stage converter was achieved well,the output voltage ripple was controled within a reasonable range,the load capacity meet the design requirements,and the power system can be stable operation in the full load range.