The input current of the two-stage DC-AC inverter contains low frequency ripple whose frequency is twice that of the inverter's output voltage. The proportion of the low frequency current ripple's amplitude to the average current's can achieve as high as more than 30%. The stability of dc power system and life span of the input voltage source such as battery or fuel cell could be influenced seriously. The reason of low frequency input current ripple production is analyzed, and the new control strategy of the first stage DC/DC converter is proposed on this paper. Compared with the traditional control strategy, the resonant controller is introduced. The proposed new control strategy is effective in reducing the current ripple in the output filter inductor of the DCIDC converter. Moreover, the input current ripple of the two-stage DC-AC inverter can be decreased. The design of the resonant controller and the system transfer function are given in the paper. The design principles of system stability are also discussed. At last, the effectiveness of proposed new control strategy to reduce the input current ripple that exists in the two-stage DC-AC inverter is verified by simulation and experimental results.
The dynamic output feedback control problem with output quantizer is investigated for a class of nonlinear uncertain Takagi‐Sugeno (T‐S) fuzzy systems with multiple time‐varying input delays and unmatched disturbances. The T‐S fuzzy model is employed to approximate the nonlinear uncertain system, and the output space is partitioned into operating regions and interpolation regions based on the structural information in the fuzzy rules. The output quantizer is introduced for the controller design, and the dynamic output feedback controller with output quantizer is constructed based on the T‐S fuzzy model. Stability conditions in the form of linear matrix inequalities are derived by introducing the S‐procedure, such that the closed‐loop system is stable and the solutions converge to a ball. The control design conditions are relaxed and design flexibility is enhanced because of the developed controller. By introducing the output‐space partition method and S‐procedure, the unmatched regions between the system plant and the controller caused by the quantization errors can be solved in the control design. Finally, simulations are given to verify the effectiveness of the proposed method.
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