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This paper deals with harmonics cancellation using pulse height modulation (PHM). This technique allows simultaneous optimization of the total harmonic distortion (THD) rate and the number of power switches. This leads to substantial reduction of the power switching losses as compared with PWM. A novel six-level inverter model is presented with three-phase output voltages having similar symmetry properties to a pure three-phase sinusoidal system. The proposed method allows canceling all even-order harmonics and integer multiples of the third-order harmonic. Switching angles and input dc voltage levels are determined so as to cancel most of the successive low-order harmonics (the most harmful to the network) starting from rank 2, allowing to shift the first nonzero harmonic far away from the fundamental. For 12 switching states per period, PHM allows to cancel harmonics from rank 2 to 10 with lower THD. A comparative study of the obtained output voltage and current shows their compliance with IEEE 519-1992 and IEC 61000-3-12 standards. [ABSTRACT FROM AUTHOR]

This paper describes a novel inverse fuzzy model based rotor flux oriented vector control approach of the induction motor. In order to obtain high performance speed response, rotor flux oriented vector control techniques are usually used to control the torque and flux separately as in direct current machines. The application of fuzzy logic in modeling of uncertainly dynamical systems is in progress'; however fuzzy modeling is one of the major topics in the field of modeling of dynamical systems. The authors has made an effort to develop an inverse fuzzy model of the vector control block applied to the induction motor to successfully improve the classical approach of the vector control. For the simulations results, it is shown that the proposed algorithm can successfully find the inverse fuzzy model that approximate the rotor flux oriented vector control block, with a compact number of fuzzy rules and membership's functions. [ABSTRACT FROM AUTHOR]