Research On Power Conversion Power Supply Quality Improvement Technology For Electric Vehicles

DCDC converters with high efficiency and power density are widely used in the field of electric vehicles.The performance indicators of DCDC converters mainly include dynamic response speed,steady-state error,wide input voltage and wide range load variation.These performance indicators of DCDC converters are closely related to the performance of electric vehicle power supply quality.Therefore,in order to improve the power supply quality of electric vehicles,these DCDC converters need to be controlled to obtain excellent performance.In this paper,PWM type DCDC converter as the research object,four kinds of digital control algorithms are designed to improve the above performance indicators.The main contents of the study are as follows:1.The load variation in a wide range of Boost converter is studied by using natural trajectory control algorithm.Firstly,the reasons why Boost converter cannot achieve the minimum voltage deviation and the fastest dynamic response speed are briefly analyzed.Secondly,in order to comprehensively consider the two indicators of voltage deviation and dynamic response speed,this paper proposes two algorithms: two-stage switching control and phase plane secant trajectory control.After introducing the derivation process of these two control algorithms in detail,the simulation results show that compared with the minimum voltage deviation control law,the proposed algorithm has faster dynamic response speed;Compared with the minimum recovery time control law,the proposed two digital algorithms have smaller voltage deviation.In particular,the proposed secant trajectory algorithm based on the phase plane can achieve a better balance between the two indexes of voltage deviation and recovery time.2.The boundary control algorithm of the natural trajectory of different operation modes is used to study the two conduction modes of the Boost converter.In order to realize the wide range load regulation of Boost converter,a multi-mode switching control algorithm is designed based on the phase trajectory in different modes.In the dynamic process of two modes switching,the algorithm has the minimum mode recovery time.3.The wide input voltage range of FSBB converter is studied by using the natural trajectory of three operating modes.In order to realize multi-mode switching in Buck and Boost modes,a multi-mode switching algorithm based on integrated trajectory of FSBB converter is designed in this paper.On the basis of achieving a wide input voltage range of FSBB converter,this algorithm comprehensively considers two indicators:dynamic response speed of mode switching,inductance current and output voltage deviation.Compared to traditional PI control and large signal natural trajectory control algorithms,the proposed integrated trajectory multi-mode switching algorithm has a good compromise.