Research On Three-phase Three-line VIENNA Rectifier

Three-phase three-line VIENNA rectifier,as a three-level rectifier,has many advantages,such as no dead-zone,no bridge arm shoot through risk,less switch counts,low voltage stress of power devices to half of the DC side bus voltage,good power factor correction effect and high power density.It has been widely studied by many researches,and has also been widely adopted in practical applications.Firstly,the operation principle and mathematical model of three-phase three-line VIENNA rectifier are analyzed in this dissertation,and its mathematical models in different coordinate systems are obtained.The three-phase three-line VIENNA rectifier adopts double-loop control strategy as a popular method for traditional rectifier.According to the mathematical model of the three-phase three-line VIENNA rectifier in the dq rotating coordinate system,the control parameters of the voltage loop and the current loop are designed.The RMS current of the bridge arm diode and switch of three-phase four-line VIENNA rectifier can be designed based on the same methodology used for single-phase Boost circuit,but there is no accurate expression of RMS current for three-phase three-line VIENNA rectifier.In this paper,the operation principle of three-phase three-line VIENNA rectifier based on space vector modulation is analyzed,and the theoretical expressions of the effective current of the bridge-arm diode and switch are derived step by step,which provides design basis for device selection,heat dissipation design and loss calculation,and the derived results are successfully verified by experiment and simulation.If the power level of three-phase three-line VIENNA rectifier needs to be further improved,considering the limitation of voltage and current rating of a single device,instead of paralleling the power devices,the parallel operation of three-phase three-line VIENNA rectifier will be more attractive due to modular design.However,it may cause circulating current among these paralleled VIENNA rectifier modules.This paper analyses the mechanism of circulating current,and presents a strategy of circulating current suppression.The control method is simulated by PLECS with two paralleled 1kW three-phase three-line VIENNA rectifiers.Simulation results verify the effectiveness of the proposed circulation suppression strategy.