Improvement Research Of Topology And Control Strategy For Dual Buck Inverter

As a kind of power electronic transform device which converts direct current toalternating current, the inverter plays a key role of continuity in many areas, such as thenew energy grid generation system, ac motor variable frequency speed regulationsystem, uninterrupted power supply system and flexible HVDC system. Compared withthe traditional inverter, the dual Buck inverter has the advantages of simple circuitstructure, no bridge arm straight, high reliability and small system loss. Absolutely, ithas some shortcomings, such as the low utilization rate of dc input voltage and loadability. So it is very important to research the topology and control strategy of the dualBuck inverter which makes it the better electrical and practical performance.Firstly, the paper reviews the present topology and control strategy of inverter, andanalyzes their respective advantages and disadvantages. Dual Buck inverter is chosen asthe research object, and its working principle is discussed. After the control strategy wasanalyzed, the paper points out dual Buck inverter with low steady-state accuracy and theload capacity under the double loop control strategy. The simulation platform has beenset up to verify the theory.Then, combining the sliding mode control theory, this paper proposes a doubleloop sliding mode control strategy to solve the above problems. After that, the paperdesigns the system modeling and the sliding mode controller, and discusses theswitching frequency. Through the simulation analysis, the results show that dual Buckinverter adopts the double loop sliding mode control with higher steady state accuracy,smaller harmonic distortion rate and stronger load ability, which has the very gooddynamic and steady state performance.Through the analysis of the dual Buck inverter topology, the paper improves theoriginal topology to overcome the low utilization rate of dc input voltage and the largemagnetic volume weight. And it selects a control strategy with four state variables forcapacitive voltage deviation x1and its differential x2, inductance current deviation x3and its differential x4. Also, this paper designs the sliding mode controller. Then, thesimulation results show that the improved topology not only increase the efficiency ofdc voltage, reduce the magnetic volume weight, but also has better dynamic andsteady-state performance, and has a stronger inhibitory effect for the dc input voltageand power grid disturbance. Finally, in order to verify the improved topology of dual Buck inverter under thedouble second-order sliding mode control strategy, the paper sets up the experimentalplatform. And it has designed the main circuit and control circuit respectively. Theexperimental results validate the correctness of the simulation analysis, and furthershows that the correctness and feasibility of the improved dual Buck inverter.