Design And Implementation Of 800W LLC DC Converter Based On STM32F334

With the development of national science and technology and the continuous maturity of power electronic technology,the concept of digitalization and green energy saving have become the mainstream development direction of various industries.Traditional power supply technology has been unable to meet the needs of the power supply market.In contrast,the switching power supply has the characteristics of high efficiency,small power consumption,small size,light weight,good dynamic performance,easy to realize intelligent control and automatic control.Therefore,it has a huge market size and the development trend is steadily rising.The current power supplies on the market are increasingly demanding high efficiency and high power density for DC-DC converters.Therefore,the use of high frequency to increase power density,the use of soft switching technology to improve the efficiency of the switching power supply came into being.LLC resonant converters perform well in terms of power density and efficiency,and are usually used in complex and high-performance systems,but the output stability of LLC resonant converters is a problem that is still being studied at this stage.The analog-type LLC resonant converter on the market has the disadvantages of large temperature drift,inadequate system monitoring and management,and slow dynamic response speed.The digital type converter is usually implemented based on DSP,which would increase the cost of the converter.In this paper,the LLC resonant converter based on STM32F334 is designed and implemented,which reduces the cost of digital power supply.It improves the dynamic response speed,reduces the temperature drift,and has good system monitoring and management functions,and has good application value.First,the article analyzes the basic working principle of LLC resonant converter,and then compares and analyzes the working principle of the upper and lower resonant regions of LLC converter.The conditions for LLC resonant converter to realize the primary side power switch ZVS turn on and the secondary side ZCS turn off are obtained.In addition,the article deduces and analyzes the gain of LLC resonant converter in detail.This part of the principle analysis provides a theoretical basis for the subsequent design of hardware circuits and software systems.Secondly,research,develop and select the hardware system of the converter,then calculate the circuit parameters.A software control system based on STM32F334 is designed,which greatly improves the performance of LLC resonant converter and saves the cost of implementing digital power supply.The design of the software system mainly includes the design of the drive signal generation of the LLC resonant converter,the design of the loop compensation to achieve stable output,the design of the control method of the bus voltage and the software design of the overcurrent and overvoltage protection.Finally,carry on software simulation to LLC resonant converter,and produce a 800 W prototype.The maximum efficiency of the actual test of the converter has reached 94%,and the output voltage under dynamic load is controlled within ± 5%.Experiments show that the voltage output is stable and the dynamic response speed is fast,the protection system is responsive,and the performance index meets the design requirements.