Research On The Topology And The Modulation Of Three-Level Inverter And Its Application In APF

In recent years, the usage of multi-level inverters has increased significantly in the power electronic applications. The increasing quantity of inverter levels makes high-quality output and low switching frequency. Besides, multi-level inverters have won more attention due to lower switching frequency. In applications, too many inverter levels have caused difficulty to control and realize. Now it is three-level inverter that is used more, and replacing two-level inverter gradually. Therefore, the research on the topology and the control algorithm of three-level inverter is very meaningful for the theory and the industrialized applications.First, the three-level inverter technology is summarized which covers the research background, the current research conditio and the prospect, attesting the significance of the research on the three-level inverter.Systematically analyze the operating principles of the main three topologies of three-level inverter and their advantages and disadvantages, including three-level inverter,Flying Capacitors and Cascade form.Analyze the fundamental principle of PWM method of the three-level inverter, including Sine carrier PWM, Harmonic elimination PWM and SVPWM, which emphasizes the implementation model of space vector PWM. For the SVPWM, it requires a lot of trigonometric function calculations or table look-up. The proposal of the three-level without Angle computing SVPWM algorithm has reduced the calculation amount of the controller and the storage space, improve the system realtime performance, facilitating the digital realization.Respectively apply this algorithm to the topology of diode clamp and cascade three-level inverter, and analyze the specific implementation approach and technical feature in details,and set up hardware circuit topology and drive circuit, and design software by DSP as controller. The experimental verification has been done for the proposal of three-level No-angle SVPWM algorithm. The experimental results prove that this algorithm can ensure unchanged output characteristics of three-level inverter and achieve good three level inversions.Three-level inverter topology and no-angle SVPWM have been applied to APF,replacing the two-level topology and control algorithm adopted in the traditional APF. Firstly,it has analyzed two kinds of conventional harmonic current detection method, including instantaneous power algorithm and FFT harmonic separation algorithm, and made a comparison about the strengths and weaknesses of these two methods and their application situations in the real industrial. Secondly, it has analyzed the performance and the product advantage of three-level inverter topology in APF. The effectiveness of the three-levelinverter theory in APF has been verified by setting up APF simulation model and adopting Instantaneous power harmonic separation algorithm, Diode clamping topology and No Angle computing SVPWM algorithm.