With the development of the medium voltage DC bus in the renewable energy integrated power supply system,the application scale of the phase-shift full bridge converter with simple structure and high efficiency in the renewable energy DC power supply system is increasing.However,when connecting the equipment with low voltage at the port and the medium voltage DC bus,a higher voltage rise ratio is required.Multiple phase-shifting full bridge topologies are connected through parallel input and series output(IPOS)to form an IPOS phase-shifting full bridge converter,which can not only provide higher voltage rise ratio,but also provide larger output power.In order to promote the application of high-power phase-shifting full bridge converter in renewable energy integrated power supply system,this thesis takes IPOS phase-shifting full bridge converter as the analysis object,and makes an in-depth study on the rectifier diode voltage spike of the converter,the design of digital controller and the parallel current sharing of polytropic converters.Aiming at the problem of high voltage spike when the rectifier diode of phase-shifting full bridge converter is turned off,the equivalent circuit model of the converter is established,the time-domain expression of the rectifier diode turn off voltage is obtained,and the formation mechanism of voltage spike is analyzed;RCD absorption circuit is used to suppress voltage spikes.While taking into account lower voltage spikes and higher power transmission efficiency,the design method of RCD resistance is proposed;Finally,the accuracy of the design method is verified by simulation and experiment.In order to ensure the static and dynamic performance of the converter,a digital controller design method based on discrete domain is proposed in this thesis;Firstly,the small signal mathematical model of IPOS phase-shifting full bridge converter is established,and the value range of controller parameters to ensure the stability of the converter is obtained based on Julie criterion.Then,the controller parameters to ensure the dynamic performance index are further determined according to the zero pole distribution diagram;The effectiveness and correctness of the design method are verified by simulation and experiment.This thesis further discusses the parallel current sharing control scheme of multiple IPOS phase-shifting full bridge converters,and studies the dynamic performance of the parallel system with current sharing control;The state space model of parallel system is established,and the influence of output power on the dynamic performance of the system is analyzed;The influence of controller parameters on the dynamic performance of the system is studied,and the optimal design scheme of controller parameters is given;The correctness of the theoretical analysis is verified by simulation. |