Control technique for high power factor multilevel rectifier

Three control techniques for a high power factor multilevel pulsewidth modulation (PWM) rectifier are proposed. The proposed rectifier is based on series connection of full-bridge cell to achieve a high power factor, low current distortion, low voltage stress of power semiconductors and two balanced output voltages. The look-up table is used in the proposed control schemes to reduce the hardware circuit. A capacitor voltage compensator is used to balance two dc capacitor voltages in order to obtain high quality PWM voltage pattern. Based on the proposed control schemes, two-level or three-level PWM pattern can be generated on the ac side of the adopted rectifier. The proposed techniques for a high power factor multilevel rectifier illustrate its validity and effectiveness through the respective simulations and experiments. According to the measured results, the current harmonics drawn from the mains meet the International Electrotechnical Commission (IEC) 1000-3-2 limits     

Decoupling the flight control system of a supersonic vehicle

In this paper, a nonlinear decoupling technique is proposed for analyzes and designs of a serious aerodynamic coupled missile flight control system. Decoupling is obtained from multiplications of two measurable accelerations with three controllable output commands of the autopilot. They give exact signs and magnitudes proportional to aerodynamic decoupling. No matrix inversion of the system dynamic for decoupling is needed. From frequency responses of the rolling channel, it will be seen that the decoupling and robustness for copping with aerodynamic couplings can be obtained simultaneously. Furthermore, the decoupling characteristics are kept almost unchanged for large system parameter variations and uncertainties. The 5-DOF simulations give same conclusions.