Design And Control Of Three-phase PWM Rectifier Based On SiC MOSFET

With the development of power electronics device,SiC as a representative of the new generation of power semiconductor devices has been widely used.Three-phase SiC PWM rectifier have advantages of low THD in input current,high power factor and high power density.However,the high frequency characteristics of other components is a danger in the application of SiC.This paper focuses on the investigation of systematic analysis of the control system.The research issues mainly include: the design of hardware circuit and controller in high frequency applications,the soloving of inrush current in the start-up time,the analysis of the nonlinear characteristics of the filter inductance.In order to analyze and design the hardware circuit of three-phase SiC PWM rectifier in high frequency.The differences between SiC MOSFET and traditional Si devices in static characteristics and switching characteristics are contrasted,The design requirements of the high frequency SiC drive are obtained,and the parameter design of the drive circuit is completed.In order to analyze and design of three-phase PWM rectifier filter,the parameters of the filter inductor and capacitor are calculated in detail.The high frequency characteristics of two kinds of elements is analyzed.The mathematical models of three-phase PWM rectifier are established in the three-phase stationary coordinate and two phase rotating coordinate,and the equivalent model of controlled object is obtained.In order to analyze and design the controller based on proportional integral(PI)and proportional integral resonance(PIR),the principle of feed forward decoupling control is analyzed and the design method of the parameters is given.In addition,the problem that the sampling frequency and the control frequency are not matched in the practical application of SiC devices are analyzed.The control system design of three-phase SiC PWM rectifier is completed.A three-phase SiC PWM rectifier prototype is built.The rationality of the design of the hardware and the control system is verified.This paper focuses on the problem that the PWM rectifier is prone to inrush current in the start-up time.The causes of inrush current are analyzed from two aspects of physical mechanism and mathematical derivation.According to the analysis of the affecting factors to inrush current,a method is proposed by limiting the output amplitude of voltage loop in the start moment.A experimental platform is used to validate the effectiveness of the proposed strategy.The filter inductor with magnetic core material has the characteristics of low loss and high magnetic density under high frequency.The nonlinear characteristics of the filter inductance are further discussed.The influence on ac side harmonics and will the performance of control system are introduced in three-phase PWM rectifier.The PIR controller can effectively suppress the odd harmonics of the input current.The rationality of the analysis on the nonlinear characteristics of the filter inductoris verified.