| With the continuous use and development of new energy sources,the daily production of electric energy is also increasing,and the use of electricity has brought a lot of convenience to people’s lives.In recent years,the mass production of automobiles has aggravated the shortage of non-renewable resources such as oil and severely polluted our living environment.In order to achieve the strategic goal of sustainable energy development,vigorously promote electric vehicles to replace fuel vehicles.If necessary,the research on electric vehicle charging technology is particularly important.Due to the difference in battery capacity and parameters,charging efficiency and time have become issues that need to be addressed.The emergence of LLC resonant converter solves the problems of low switching frequency and low transmission efficiency of traditional DC-DC converters,and it has soft switching characteristics,which further reduces the energy loss during transmission.It is widely used in the power supply industry.The LLC resonant converter itself has a large current output ripple and low power,so two interleaved parallel technology can be used in the charging technology.However,due to the difference of the resonant cavity parameters,the two output currents cannot be divided equally,which makes the converter It cannot work normally.Therefore,on the basis of the existing technology,it is the key to solve the problem to find a two-channel current sharing control method.This article mainly studies the control technology of the interleaved parallel LLC from the following aspects:First,the development history and basic theory of the interleaved parallel LLC technology and its current sharing control are introduced in detail,the fundamental equivalent model of the interleaved parallel LLC is established,the circuit working principle is described,and the voltage gain and various parameters are analyzed.The relationship between provides a theoretical basis for the parameter design and optimization of subsequent experiments;Secondly,the working principle of pulse frequency modulation of the interleaved parallel LLC is introduced in detail,and the influence of the difference of the resonance tank parameters on the output current sharing is analyzed.On this basis,the phase shift control method is introduced,and the relationship between the phase shift angle and the voltage gain is qualitatively analyzed.Adopt the two kinds of control of frequency modulation and phase shift to be applied to the interleaved parallel LLC,which solves the problem of uneven current caused by parameter difference,optimizes the parameter design for the main circuit,and makes the output waveform more stable.Finally,use MATLAB/Simulink to establish a simulation model of the interleaved parallel LLC resonant converter,and analyze the simulation waveform based on the theory.At the same time,an experimental platform is built.The TMS320F28035 is selected as the main control chip to conduct experimental tests and analyze the experimental waveform.The rationality and effectiveness of the proposed control method can well solve the uneven current problem of the interleaved parallel LLC resonant converter. |
