Study On Efficiency Improvement Of Three Phase PWM Rectifier

Three phase voltage source PWM rectifier, due to its remarkable features of high input current power factor and low harmonics is widely used in direct-current (DC) source and uninterrupted power supply (UPS). As the requirement for efficiency is more and more crucial in modern power electronics application, it is very important to improve the efficiency of the three phase PWM rectifier.Soft switching technology can reduce the switching loss of PWM rectifier.The Compound Active Clamping (CAC) ZVS three phase PWM rectifier has a simplified topology and can be controlled by SVM strategy, it’s one kind of promising soft switching technology.The circuit of CAC rectifier is same with ACRDCL, but the control method and the working principle are differient. Resonant inductor is the improtant part of the auxiliary resonant branch, it realizes ZVS operation for all switches with the resonant capacitors. The design of the resonant inductor not only decides the work of the circuit, but also influences the power loss of the resonant branch,which is relative to the efficiency of the rectifier. A resonant inductor of ferrite is designed according to the working condition of the30kW CAC PWM rectifier. In order to optimize the resonant inductor, then a sendust inductor is designed, the power loss、volume and weight of the two inductors are also compared. Different resonant inductor is used to experiment on the30kW CAC PWM rectifier.New power device is another way to improve the efficiency, SiC MOSFET has the advantage of high blocking voltage, low conduction loss, low switching loss and can work under high temprature, wich contribute to high efficiency and high power density. Suitable driver circuit is the base of applying power devices. The drive voltage of SiC MOSFET is unique to the Si device. One kind of driver circuit for1200V SiC MOSFET is proposed, the influence of drive resistance and drive voltage on switching characteristics is analysized by the double pulse circuit, which offers guide for designing SiC MOSFET driver circuit.Then the switching characteristics of differient current is analysized,which offers reference for the application of SiC MOSFET.