| The goals of "Carbon Peak" and "Carbon Neutralization" have been promoting the development of new energy field.The LLC Digital Power Supply based on LLC resonant converter has the characteristics of high efficiency,high integration and intelligence,and is widely used in new energy fields such as new energy vehicles,aviation power supplies and photovoltaic power generation.However,the LLC Digital Power Supply is too complex to design,which will produce inrush current during startup,which will affect the design cost and safety of the power supply.In order to solve the above problems,this paper provides a reference design scheme of LLC Digital Power Supply,and puts forward a soft-start control strategy of LLC Digital Power Supply.The overall work of this paper is as follows:First of all,by analyzing the structure and working principle of the LLC resonant converter,using the fundamental frequency component method to build the equivalent model,establishing the relationship between the relevant parameters,the gain characteristics of the LLC resonant converter and its influencing factors are obtained.Aiming at the cause of inrush current during the start-up of LLC Digital Power Supply,the characteristics of existing soft-start schemes are analyzed,and the relationship between frequency adjustment gain,duty cycle adjustment gain and total gain is obtained by simulation,and a linear compensation soft-start control strategy is proposed.According to the relationship between the frequency adjustment gain,the duty cycle adjustment gain and the total gain,this strategy uses the frequency adjustment gain to linearly compensate the duty cycle adjustment gain,so that the total gain tends to linear,and the startup current can be better suppressed.Secondly,in view of the problems that may occur in the design of LLC Digital Power Supply,the hardware parameters and circuits of LLC Digital Power Supply are designed according to the principle.Based on the hardware design,the software program is designed,and the related programs such as interrupt control,soft start,PI control and security protection are written,and the correctness of the design is verified by simulation.Finally,an experimental prototype of LLC Digital Power Supply is built for testing.The test results show that the experimental prototype can stably output 12V～28V voltage,the maximum full load efficiency is 94.2%,the ripple of rated output voltage is 240 m V,and the load adjustment rate is 0.5%.Compared with other soft-start schemes,linear compensation softstart can shorten the duty cycle adjustment time by 20%,and achieve better current suppression effect. |
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