| In recent years,electric vehicles have become a hot spot in the automotive industry and its sales are growing rapidly.Electric vehicles with high efficiency,environmental protection,energy saving and many advantages gradually become a new vehicle to replace fuel vehicles.Its development has been widely supported by governments all over the world,and it has carried out the concept of sustainable development of economy and society.The construction of electric vehicle charging station is the premise and basis for the healthy development of the electric vehicle industry.A complete charging station mainly includes power supply system,charging system,monitoring system and other auxiliary equipment.The charging system includes AC charger and off-board charger,which is the core equipment.This paper focuses on the three-phase PWM rectifier that is the key equipment of off board charger.Based on the key technical indexes of harmonic current,power factor,efficiency,temperature and reliability in the network side,the software and hardware are both analyzed and designed.Finally,through building the simulation and experimental platform of off-board charger,the feasibility of the designed three-phase PWM rectifier is verified.The main contents of this paper are as follows:Firstly,the design index of high power PWM rectifier is proposed,and the topology of high power PWM rectifier is selected and the system model is established.The mathematical model of three-phase PWM rectifier in different coordinate system is deduced and analyzed in detail.The selection of DC side voltage of three-phase PWM rectifier is discussed.According to the power index and the transient current tracking index,AC inductance and DC side capacitor parameters are designed.Secondly,a dual closed loop control strategy based on quasi proportional resonant controller(QPR)for PWM rectifier is proposed.The performance indexes and advantages of QPR are studied.Parameter design formula is derived in continuous and discrete domains.According to the static and dynamic requirements,the current loop parameters and the outer loop parameters of PWM rectifier are designed.The control performance of double closed loop and the function of each feedforward loop are studied and analyzed.The phase accuracy of the phase locked loop is improved by optimizing the digital phase locked loop.In this paper,the space vector modulation algorithm and its implementation steps are introduced in detail,and the advantages and disadvantages of the two methods are compared.In the end,the performance of the PWM rectifier and the control strategy are verified by simulation.An experimental platform for high power PWM rectifier is developed,which is suitable for off-board charger.The voltage and current acquisition circuit,the drive circuit and the main control circuit are studied,as well as the software program.The dynamic and static characteristics of the prototype,control loop,optimization effect of digital phase locked loop and the influence of different space vector synthesis are tested on the experiment platform of high power three-phase PWM rectifier.The simulation and experimental results show that the designed high power three-phase PWM rectifier in this paper can satisfy the performance index of off-board charger.It has the advantages of low current distortion,high power factor,high efficiency,low loss.Research results of this paper can provide reference and guidance for high power three-phase PWM rectifier in the field of off-board charger. |
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