| With the deteriorating ecological environment,energy problems become more serious,in which electric vehicles with its low-carbon and environmental protection advantages of much attention,electric vehicle development has been the strong support,smart grid and V2G(Vehicle-to-Grid)technology is widely studied based on this.The orderly charge and discharge of electric vehicles through the smart grid can not only play the role of peak and valley filling,but also reduce the operating cost of the grid and improve the stability of the grid.Power electronics technology occupies a very important position in V2G technology.It can realize the two-way flow of power grid and electric vehicle energy,which has important research value and significance.This paper mainly studies the design and hardware implementation of bidirectional AC-DC converter based on V2G background.Firstly,it introduces the development direction and existing power supply methods of V2G technology,the three types of domestic electric vehicles,and the development status and research overview of V2G technology at home and abroad.At the same time,the circuit topology commonly used in V2G technology is analyzed,a variety of single-stage and two-stage AC-DC topologies are compared,and the theoretical analysis advantages and disadvantages of these topologies are studied.Secondly,the mathematical modeling of the bidirectional AC-DC conversion is carried out,and the transfer function between the DC bus voltage and the AC current amplitude is derived,which provides a basis for simulation modeling.The theory analyzes the basic working principles,advantages and disadvantages of the dual Boost and totem pole modes,and finally selects the totem pole as the MOS tube working mode.In order to filter out the interference of common mode noise and differential mode noise on the system,the electromagnetic interference(Electromagnetic-Interference,EMI)filter circuit is analyzed and designed,calculation and selection of the inductance value of the bridge arm side and the DC bus capacitance value,at the same time,the main loss of the circuit is analyzed,including the power switch tube loss,conduction loss and inductance loss.Thirdly,the four control methods of inductor current control,deadbeat control,traditional digital PID control and digital PID control based on proportional resonance(Proportion-Resonant,PR)are studied.The control algorithm is theoretically derived,the advantages and disadvantages are analyzed,the voltage and current double closed-loop control strategy is analyzed.Before implementing the control algorithm,analog phase lock and digital phase lock are introduced.In view of the problem that the traditional software phase lock has a long phase lock period and uncertainty,an enhanced capture module(ECAP)based on Enhanced Capture Module(ECAP)was proposed.)Software phase-locking method to ensure the accuracy of phase-locking while increasing the phase-locking speed,theoretical analysis of the four phase-locking methods,hardware cost and volume considerations.Finally,the digital PID control based on PR and the software phase-locking method based on ECAP are selected.Finally,simulation analysis and experimental verification of bidirectional AC-DC conversion are carried out.The model is built based on MATLAB/Simulink simulation platform,comparing the traditional digital PID control and PR-based digital PID control of the AC current harmonic components,the DC bus voltage waveforms during load cutting and voltage cutting,and the simulation analysis verifies the PR-based digital PID control effect is better,and the DSP28035 digital signal processing chip is used to write a program and make a prototype.The experimental results verify the correctness of the control algorithm.In addition,the problems of traditional software phase-locked loops are verified through simulation analysis.Based on the ECAP-based software phase-locking method,the voltage phase of the power grid can be locked in one power cycle.The methods were compared and verified. |
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