The energy produced using a photovoltaic (PV) is mainly dependent on weather factors such as temperature and solar radiation. Given the high cost and low yield of a PV system, it must operate at maximum power point (MPP), which varies according to changes in load and weather conditions. This contribution presents an improved maximum power point tracking (MPPT) controllers of a PV system in various climatic conditions. The first is a sliding mode MPPT that designed to be applied to a buck converter in order to achieve an optimal PV array output voltage. The second MPPT is based on the incremental conductance algorithm or Perturb-and-Observe algorithm. It provides the output reference PV voltage to the sliding mode controller acting on the duty cycle of the DC-DC converter. Simulation is carried out in SimPower toolbox of Matlab/Simulink. Simulation results confirm the effectiveness of the sliding mode control MPPT under the parameter variation environments and shown that the controllers meet its objectives.

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This paper treats a speed-sensorless drive of a three phase Induction Motor (squirrel-cage). The purpose is to implement an electric traction system, based on the use of 1M controlled by power electronic converter. This system allows the speed control of the vehicle, forward, backward and regenerative braking. The four quadrants operation is required. The developed control strategy is based on classical Direct Torque and Flux Control (DTC). Both rotor speed controller and rotor speed estimator are based on fuzzy logic controller (FLC). The obtained control performances are shown by simulation using MA TLAB and its toolbox SIMULINK.

<span lang="EN-US">Multilevel power converters are becoming increasingly used in several sectors: energy, grid-tie renewable energy systems, High voltage direct current (HVDC) power transmission, and a multitude of industrial applications. However, the multilevel converters consist of several drives and a high number of power switches, which leads to a considerable cost and an increased size of the device. Thus, a novel topology of a multilevel bidirectional inverter using a reduced number of semiconductor power components is proposed in this paper. Without any diode clamped or flying capacitor, only nine switches are used to generate nine voltage levels in this new topology. The proposed multilevel converter is compared with the conventional structures in terms of cost, the number of active power switches, clamped diodes, flying capacitors, DC floating capacitors, and the number of DC voltage sources. This comparative analysis shows that the proposed topology is suitable for many applications. For optimum control of this multilevel voltage inverter and to reduce switching losses in power semiconductors, a hybrid modulation technique based on fundamental frequency modulation and multi-carrier-based sinusoidal pulse-width modulation schemes is performed. The effectiveness of the proposed multilevel power converter is verified by simulation results.</span>