Research On The Active Power Filter Based On Three Level SVPWM

In recent years, Active Power Filters (APF) exhibits some excellent performances ineliminating harmonics and compensating reactive, so it develops rapidly. Due to the limit ofthe rated capacity of the power switch, APF based on the structure of the two-level invertercannot be applied to high-power, high-voltage occasions directly. The three-level inverterstructure can take advantage of the power switching devices of the low voltage level toachieve the high-voltage output, and under the same switching frequency, it only has smallcurrent harmonic in AC side, low voltage to conduct, small switching loss, high efficiency.Therefore, this paper proposes to research an high-performance APF based on the three-levelinverter structure, the research includes the followings:First, describe about the background and significance of this research project, introductresearch status of the three-level APF, and analyze existing problem of three-level APF, sodetermine the main content.Secondly, analysis is based on the basic working principle of three-level APF, comparethe three-level PWM modulation technique, elaborate the principle of the three-level spacevector pulse width modulation (SVPWM) algorithm.Thirdly, for solving the imbalance of the DC side midpoint voltage of diode clampthree-level inverter, describes advantages and disadvantages of the current common method ofthe midpoint voltage control based on hysteresis SVPWM modulation, and then propose themethod of the midpoint voltage to control SVPWM modulation based on the charge balanceof the DC side capacitor. Compared with the former, the control strategy is clearer, can get thesmaller range fluctuation of the midpoint voltage.Fourthly, use dq0Detection method of instantaneous reactive power theory based ontime-domain, introduce the brain emotional algorithm with PI control and self-correction intothe tracking control of harmonic current, the algorithm can overcome optimization problem ofPI parameters of the current common PI control based voltage oriented, so further improvesthe dynamic-static performance.Finally, the paper simulates in the MATLAB simulation environment, which is in twospecial cases of the three-phase balance disturbance and three-phase unbalance disturbance.According to the model, complete TMS320F28335controller design and its main circuitdesign.The simulation and experimental results show that the three-level APF not only canreduce the power grid harmonic and compensate reactive power, also can suppress the three-phase unbalanced, while maintaining the balance of the DC side of the midpoint voltage.Therefore, the APF has a certain significance and application value.