Research On Tolerant Control Of T-topology Active Power Filter

With the rapid development of power electronics technology,power electronic devices have the advantages of fast response and low power,but at the same time,a large number of harmonics have been brought to the power grid.China is in the stage of great rejuvenation,and the demand for green and clean energy is increasing.Active filter is widely studied and applied in power network filtering because of its good filtering function and excellent dynamic response.The main inverter circuit is an important part of the active filter,because the power electronic devices in it are often in high-temperature and high-frequency working state,which is prone to failure.It is of great significance to judge the fault location in time and to operate fault-tolerant in the failure state.Based on a large number of literatures,this paper first establishes the research purpose and significance of active filter.Then the structure and operation principle of the active filter with T-type topology are introduced.SVPWM modulation algorithm is used for active filter with T-type topology,and its mathematical model in three-phase static coordinate system and two-phase rotating coordinate system is established.The changes of output voltage and current path before and after the failure of the vertical and horizontal arm of the power electronics device are introduced.On this basis,the basis for judging open-circuit failure is presented and classified.The accuracy is verified by MATLAB/Simulink simulation.Three fault-tolerant control schemes are proposed for different types of open-circuit faults,a fault-tolerant scheme replaced by redundant vectors is proposed for open-circuit faults of horizontal arms,and a fault-tolerant scheme for open-circuit faults of vertical arms is proposed.A new three-phase eight-switch topology fault-tolerant scheme is proposed for the open circuit faults with mixed vertical and horizontal bridge arms,and the three-level SVPWM is improved accordingly.The accuracy is verified by simulation validation with MATLAB/Simulink and experiments on the experimental platform.