Research On Three-Level Flying Capacitor Buck-Boost For 5G Power Amplifier

In recent years,with the booming development of 5G technology,people’s demand for high-speed data communication is increasing day by day.However,due to the dramatic increase in energy consumption and limited expansion space of 5G base station,the higher efficiency and higher power density of 5G power amplifier(PA)power supply are increasingly demanded in the market.The traditional 5G PA power supply generally adopts full bridge isolation topology.Its transformer size is large and will cause additional loss,which makes it difficult to further improve efficiency and power density.Therefore,the following studies are carried out according to the high efficiency and high power density requirements of 5G PA power supply.Firstly,the power supply modules in the existing industry are investigated,and the advantages and disadvantages of isolation topology,traditional non-isolation topology and Three-Level non-isolation topology with flying capacitor are compared and analyzed.Because multi-level technology can reduce volt-seconds of inductor,greatly reduce the volume of inductor,and use MOSFETs with lower breakdown voltage and better performance,it is possible to further improve efficiency and power density.Therefore,this paper chooses Three-Level Buck-Boost as the research object.Secondly,in order to achieve high efficiency and power density,the selection method of switch and the design of inductor,capacitor and other device parameters are given for the two-phase interleaving flying capacitor Three-Level circuit,and the Tunnel Magneto Resistance(TMR)current detection scheme with small volume and low delay time is selected.The open-loop small signal model of Three-Level topology is established.The closed-loop small signal models of voltage mode control and average current mode control are compared and analyzed.The dynamic multi-stage control method of output voltage regulation is proposed,and the fast voltage regulation is realized.The effect of flying capacitor voltage compensation is compared under different carrier modulation modes,and the carrier modulation scheme suitable for this scheme is selected.Finally,a 1 k W prototype of two-phase interleaving Three-Level Buck-Boost with97.5% peak efficiency and 510W/in3 power density is developed,which verifies the reliability of the design method and achieves the expected target of high efficiency and high power density.