Research And Design Of Bi-drectional PWM Rectifier

Power electronic equipment with rectifier is widely used in industry and daily life. In the equipment uncontrolled rectification or phase-controlled rectification is mostly employed for simplifying the AC-DC conversion stage. But the rectification can produce a lot of harmonics, consume reactive power and reduce power factor. In order to restrain harmonics in electric power system, many countries in the world have set up related standards to limit the use of disqualified power electronic equipment.Nowadays there are two methods to limit harmonics and correct power factor: one method is passive power factor correction, and the other is active power factor correction. The active power factor correction is to adopt full controlled switching devices in the main circuit and pulse-width modulation to eliminate harmonic and improve power factor. Based on analyses a bi-directional PWM rectifier with the active power factor correction is designed and presented in this thesis.Several circuit topologies of rectifier are compared firstly in this thesis. The three-phase bridge voltage source PWM rectifier is focused in the research due to its advantages. Then the rectifier circuit principle, the main circuit switching process and the mathematic model in ABC and d-q coordinate are proposed in the thesis. The theory of SVPWM is also analyzed and a digital realization is achieved. Moreover, detailed designs of the main circuit include AC inductors, DC capacitors, IGBTs and snubber circuit are given in the thesis. The main circuit and control circuit simulation results prove the feasibility and applicability of the design.SVPWM is implemented in the bi-directional PWM rectifier. The advantage of the application is not only to eliminate harmonic and improve power factor, but also to enhance the DC voltage utilization and to reduce the switch frequency.