The Optimal Design Of Three Phase Current Source Rectifier Based On SiC Power Device

With the population growth and global warming,many countries pay more attention to energy saving,in which power electronics plays an important role,such as energy power,smart grid and electric vehicles.Current source PWM rectifier as a buck rectifier has a great advantage in step-down application and is winning more market with the development of the wide band gap devices.Therefore,this thesis is dedicated to the optimal research on SiC-based PWM current source rectifier.A dual-source driver is firstly designed for SiC BJT,a powerful competitor for IGBT.Since the SiC BJT is a current mode device,the high performance driver for SiC BJT is one of keys to commercialize SiC BJT.In order to overcome the reverse current and voltage clamp problems of the dual source resistance-capacitance driver,this thesis proposes a new driver,dual source resistor and sequence control base driver.Two drivers are simulated by LTSPICE respectively and the prototypes are also established to verify the good performance of the proposed scheme.Secondly,the power loss of the three-phase current source rectifier is modeled and the switch cell is optimized,which is composed of power transistor and diode and means great power loss.Therefore,silicon carbide devices are applied in switch cell and four kind switch cells are researched and compared based on simplified commutation topology.The experimental results imply the great advantages of silicon carbide devices both in switching and conducting performance.Then,the overlap time optimization of the current source rectifier is studied.First,the influence of the overlap time is analyzed in detail,including the influence on the commutation process,the power loss and the grid-side current.The commutation process is discussed in two cases and modeled to calculate the commutation time.The influence of bus voltage and load current on commutation is researched based on simplified commutation topology.Then,an adjustable overlap time scheme is proposed,which can accelerate the commutation process at low bus voltage,and the new scheme is verified by experiment.Finally,a prototype of the 3kW SiC-based current source rectifier is established.The comparison between Si-based and SiC-based rectifier is analyzed in different aspects,including volume,efficiency and cost,which demonstrates the advantages of silicon carbide devices.