Investigation On Low Current Harmonic Control Of PWM Converter Of Energy Feedback System

With the worsening environmental crisis, renewable energy has become the demand of the development of modern society, while seeking new energy sources, energy conservation is crucial. Energy feedback grid-side converter has played a important role in energy conservation. With the increasing capacity of the power electronic devices, its impact on the power grid are becoming increasingly significant. Therefore, the energy feedback power system must meet the demanding requirements, that the feedback current quality of energy feedback systems must be good. With independent intellectual property rights, core technologies, and reasonably priced products are developed for the domestic energy feedback converter market. This paper do some systematic and deep research on the most fundamental and applied the energy feedback converter including related theoretical and application issues.The following two aspects of control strategies were mainly discussed in this paper. On the one hand, back to the grid current harmonics control strategy is sought based on energy feedback system. On the other hand, the method is sought to ensure the DC bus voltage stable when system feedback energy to the grid.Predictive current control strategy was introduced to control the current harmonics. Firstly, based on the principle of the predictive current control strategy, the mechanism and different targets of the predictive current control strategy in the stationary coordinate frame and the rotating coordinate frame was studied and outlined. This paper summarizes the mainstream current predictive current control algorithm and provide an improved predictive current control algorithm in the rotating coordinate frame. The algorithm inherits the characteristics of low current harmonics, also overcome the shortcomings of the traditional predictive current control algorithm, which include the current steady-state error, and finally achieve a good static and dynamic characteristics.The closed-loop control of DC voltage was modeled and analyzed in order to ensure the stable operation of the system by adding the sampling of the DC side current to compensation current error when the load mutation. Moreover a DC bus voltage soft-start program was developed to overcome the grid current overshoot.An experimental prototype of a DSP-based control of the energy feedback system was established and experimentally studied based on the design and analysis in the previous chapters. In addition, the protection measures was designed to improve of the system, including over-current protection, over-voltage protection and phase sequence error, based on the original hardware platform for the practical application. The main system software was accurately designed and solver the interference problem of the actual operation of the system.Through the research and experimental results, it can be verified that the key technologies for energy feedback system described in this paper, including control strategy, the main circuit design and the practical application method is viable and effective, which can guide the actual R & D and production of the energy feedback converter.