Ammar Masaoud

Xilinx FPGA Based Multilevel PWM Single Phase Inverter

In this paper a XILINX FPGA based multilevel PWM single-phase inverter was constructed by adding a bidirectional switch to the conventional bridge topology. The inverter can produce three and five different output voltage levels across the load. XILINX FPGA is a programmable logic device developed by XILINX which is considered as an efficient hardware for rapid prototyping. It is used as a PWM generator to apply the appropriate signals to inverter switches. In addition to XILINX FPGA, Matlab/Simulink software was used for simulation and verification of the proposed circuit before implementation, Simulation and experimental results show that both are in close agreement.

New Three-Phase Multilevel Inverter With Reduced Number of Power Electronic Components

In this paper, a new configuration of a three-phase five-level multilevel voltage-source inverter is introduced. The proposed topology constitutes the conventional three-phase two-level bridge with three bidirectional switches. A multilevel dc link using fixed dc voltage supply and cascaded half-bridge is connected in such a way that the proposed inverter outputs the required output voltage levels. The fundamental frequency staircase modulation technique is easily used to generate the appropriate switching gate signals. For the purpose of increasing the number of voltage levels with fewer number of power electronic components, the structure of the proposed inverter is extended and different methods to determine the magnitudes of utilized dc voltage supplies are suggested. Moreover, the prototype of the suggested configuration is manufactured as the obtained simulation and hardware results ensured the feasibility of the configuration and the compatibility of the modulation technique is accurately noted.

Sensor and sensorless fault tolerant control for induction motors using a wavelet index.

Fault Tolerant Control (FTC) systems are crucial in industry to ensure safe and reliable operation, especially of motor drives. This paper proposes the use of multiple controllers for a FTC system of an induction motor drive, selected based on a switching mechanism. The system switches between sensor vector control, sensorless vector control, closed-loop voltage by frequency (V/f) control and open loop V/f control. Vector control offers high performance, while V/f is a simple, low cost strategy with high speed and satisfactory performance. The faults dealt with are speed sensor failures, stator winding open circuits, shorts and minimum voltage faults. In the event of compound faults, a protection unit halts motor operation. The faults are detected using a wavelet index. For the sensorless vector control, a novel Boosted Model Reference Adaptive System (BMRAS) to estimate the motor speed is presented, which reduces tuning time. Both simulation results and experimental results with an induction motor drive show the scheme to be a fast and effective one for fault detection, while the control methods transition smoothly and ensure the effectiveness of the FTC system. The system is also shown to be flexible, reverting rapidly back to the dominant controller if the motor returns to a healthy state.

Design and Implementation of a New Multilevel DC-Link Three-phase Inverter

This paper presents a new configuration for a three-phase multilevel voltage source inverter. The main bridge is built from a classical three-phase two-level inverter and three bidirectional switches. A variable DC-link employing two unequal DC voltage supplies and four switches is connected to the main circuit in such a way that the proposed inverter produces four levels in the output voltage waveform. In order to obtain the desired switching gate signals, the fundamental frequency staircase modulation technique is successfully implemented. Furthermore, the proposed structure is extended and compared with other types of multilevel inverter topologies. The comparison shows that the proposed inverter requires a smaller number of power components. For a given number of voltage steps N, the proposed inverter requires N/2 DC voltage supplies and N+12 switches connected with N+7 gate driver circuits, while diode clamped or flying capacitor inverters require N-1 DC voltage supplies and 6(N-1) switches connected with 6(N-1) gate driver circuits. A prototype of the introduced configuration has been manufactured and the obtained simulation and experimental results ensure the feasibility of the proposed topology and the validity of the implemented modulation technique.

A New Five-level Single-phase Inverter Employing a Space Vector Current Control

Abstract This article introduces a new five-level single-phase voltage source inverter. The proposed configuration employs two bidirectional switches. Since some switches share the same gate signals, the proposed circuit significantly contributed in reducing the utilized power electronics components, gate drive circuits, and system complexity. A novel space vector current control strategy was employed to maintain the desired number of voltage levels based on load current. With the proper selection of the redundant inverter switching states, the deviation in neutral-point voltage was considerably minimized. The proposed work was simulated and its hardware was manufactured.

A simple modulation based maximum boost control strategy for three-phase quasi Z-source inverter

This paper proposes a new conceptual control method for three-phase quasi-Z-source inverter (qZSI) - operating under the One Dimension q-Z-Source Inverter (ODqZSI) which is based on the Single-Phase Modulator technique. The notable feature of the proposed control scheme compared with the space vector modulation strategy is its inherently reduced computational processing time. The obtained simulation and hardware results ensured the feasibility and validate the performance of ODqZSI modulation method applied to each phase. The proposed control procedure is easier for digital implementation with less computation condition and will be beneficial and effective for the further industrial applications of the qZSIs. The simulation results are actually carried out using Matlab/Simulink approach and hardware performances have been provided and discussed.