The Study Of DC/DC Converter Based On Switched-capacitor Network

With the development and utilization of new energy sources in the world,the level and capacity requirements of multilevel inverters are becoming higher and higher.In the case of multilevel inverter topology research has been mature,increasing the number of output levels is a simple and effective solution.However,in the low output level applications such as space vector control,predictive control,and so on,there are obvious defects in the application of high output power.According to the characteristics of hysteresis control technology,application of hysteresis control to complete the control of high level inverter is a good choice,but the logical expression is too complex,the tracking error and not fixed switching frequency faults.Therefore,the research of multilevel inverter hysteresis control provides a new idea for multilevel inverters.First of all,this paper describes the control technology of multi level inverter,analyzes the basic principle of hysteresis control and deduces the calculation formula of the switching frequency and the tracking error.The traditional hysteresis control of nature by area division is established in the form of tracking error and the output level of one of the mathematical relationship between the fundamental reason that hysteresis control from the complex logic.Then,aiming at the shortcomings of the traditional three level hysteresis control,a control strategy of the three level hysteresis loop without dead zone is proposed.In the positive and negative half cycle,the two hysteresis loops are used as the 0 level region or the dead zone.Compared with the traditional three level hysteresis control method,the tracking error reduces the width of the single dead band.We derive a mathematical relation between switching frequency and ring width,by dynamically adjusting the width of ring to achieve the constant frequency hysteresis control strategy,and the compensation network of positive and negative half weeks to achieve an average tracking error within a cycle of 0.Then,the tracking error is taken as the new controlled quantity,and the three level hysteresis control method based on tracking error variation is proposed.The method establishes the corresponding relationship between the change of tracking error and the increment of the level,and then selects the output level of the next cycle,thereby eliminating the setting of the dead time width and simplifying the switching logic.The control method is extended by three level Hysteresis Based on tracking error variation of the ring,and puts forward the control strategy of multilevel hysteresis tracking error variation based on multilevel inverter which can be directly applied to arbitrary levels.The method is simple and has only one parameter variable,which simplifies the design difficulty of hysteresis control in high level inverters.The method is used to realize the control strategy,which is used as the graph method,the truth table method and the programming method.Finally,the simulation and experiment platform is built,and the correctness and feasibility of the method are verified in the case of off grid and D-STATCOM application.