| In the early 1950 s,the switching power supply has been developed for using in high-tech fields such as launch vehiclesthe.In the following half century,the switching power supply has gradually become more and more popular due to its advantages of small size,low cost and high efficiency.It has replaced the traditional phase-controlled power supply as the power supply for various electronic equipment,and has achieved further development and application.In the 21 st century,with the development of semiconductor technology and materials and the breakthrough of IC field,switching power supply ushered in a new development opportunity,multi-output switching power supply has become a new development hotspot.At present,the multi-output switching power supply related technology has been relatively mature,but more and more electronic equipment for the accuracy of power supply put forward new requirements,to solve the multi-output switching power supply cross-regulation rate problem has been imminent.This paper designs a high-precision two-output switching power supply based on SiC MOSFET,using a flyback circuit of SIMO structure.The input voltage is 30 V,the main circuit output is 15 V,the auxiliary circuit voltage is variable,the maximum output voltage is 20 V,the maximum power of the circuit is 50 W,and the main circuit working frequency is200 k Hz.The working frequency of the auxiliary circuit is 450 k Hz.In this paper,the main loop feedback and driving circuit and the auxiliary loop feedback and driving circuit are designed to achieve independent control and output of the two outputs and improve the problem of cross regulation rate.At the same time,the auxiliary circuit cascade Buck circuit based on the traditional flyback circuit,realizing the function of variable output voltage of the auxiliary circuit,improving the range of output voltage and increasing the universality of the circuit.In this paper,a high-precision two-output switching power supply based on SiC MOSFET is designed,using a flyback circuit of SIMO structure,the input voltage is 30 V,the output of the main circuit is 15 V,the voltage of the auxiliary circuit is variable,the maximum output voltage is 20 V,the circuit The maximum power is 50 W,the working frequency of the main loop is 200 k Hz,and the working frequency of the auxiliary loop is 450 k Hz.In this paper,the control and drive circuits of the two outputs are designed respectively,and the independent control and output are realized for the two outputs,which improves the problem of the cross regulation rate.At the same time,the auxiliary circuit cascades the Buck circuit based on the traditional flyback circuit,which realizes the function of variable output voltage of the second outputand improves the universality of the circuit.In order to realize the circuit designed in this paper,the main research content of this paper is :(1)Summarizes the domestic and foreign research and development status and trends of multi-output switching power supplies,and summarizes the various methods and advantages and disadvantages of dealing with the cross-regulation problem;(2)The principle of the twoway output flyback DC/DC converter designed in this paper is analyzed.In addition,this paper also analyzes the non-ideal factors of the cross-adjustment rate,which lays a theoretical foundation for subsequent research and design.(3)It has become the selection and design of planar transformers,etc.,and built a simulation platform based on Cadence Orcad software,and carried out software simulation verification for the designed circuit;(4)On the basis of simulation and verification,based on EDA software,the hardware circuit design of the circuit,the drawing of the PCB layout,the selection of power switch tubes and other devices are completed,and the welding and testing of the experimental model are completed.. |
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