Research On Bidirectional DC/DC Converter Based On Sliding Mode Controller Of Electric Vehicle

With the development of the automobile industry,energy shortage and environmental pollution have become increasingly serious,and the zero pollution of electric vehicles has made it an inevitable trend in the development of the world automobile industry.However,the energy problem of electric vehicles has always been an important factor affecting the development of electric vehicles.There are many deficiencies in the single battery as a single energy source.Therefore,the auxiliary power system composed of battery,super capacitor and bidirectional DC/DC converter can be better.To meet the energy needs of electric vehicles.The bidirectional DC/DC converter can make the energy flow in both directions,which plays an indispensable role in the electric vehicle auxiliary power system.This article first introduces the working characteristics of supercapacitors and power batteries,and explains the role of bidirectional DC/DC converters in the auxiliary power system of electric vehicles.According to the requirements of electric vehicles for bidirectional DC/DC converters,various parameters of different converter topologies are compared,and a non-isolated bidirectional half-bridge topology is determined.In order to reduce the inductor current ripple and improve the power level,a two-phase interleaved parallel structure was adopted.Finally,the main topology of the converter was determined as a two-phase interleaved bidirectional half-bridge structure.In order to reduce switching losses,controlled soft switching technology is applied.The working principle of the bi-directional DC/DC converter based on soft switching technology is analyzed in detail,and the realization conditions of soft switching technology are given.Secondly,small-signal modeling of the Boost mode and Buck mode of the bi-directional DC/DC converter is performed respectively,and the transfer functions of voltage and duty cycle and current and duty cycle in both modes are derived.According to the characteristics of frequent starting and stopping of electric vehicles,the bidirectional DC/DC converter adopts sliding mode control algorithm to improve the dynamic response characteristics of the system.Using the state space equation of the bi-directional DC/DC converter,the sliding mode surface equation and sliding mode control equation of Boost mode and Buck mode are deduced,and the design of sliding mode control algorithm is completed.Then,design the hardware circuit and software program for the bidirectional DC/DC converter prototype.According to the working principle of the converter,the main components of the main circuit are designed and selected.It also includes the design of the voltage sampling conditioning circuit,the current sampling conditioning circuit,the driving circuit and the auxiliary power circuit in the control circuit and the selection of the main components.At the same time,for the DSP(Digital Signal Processing)controller,the programming of the bidirectional DC/DC converter system is completed.Finally,based on the analysis of the bidirectional DC/DC converter topology and the design of the control algorithm,under the simulink environment in MATLAB,a bidirectional DC/DC converter model is established,which verifies the practicability of the converter topology and the feasibility of the control algorithm.Sex and effectiveness.A bidirectional DC/DC converter prototype was developed.Through debugging and experiments of the prototype,important waveforms and data of the bidirectional DC/DC converter were obtained.The total inductor current ripple,dynamic response characteristics,and The interference ability and the efficiency of the whole machine meet the requirements of electric vehicles for bidirectional DC/DC converters.