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In this paper the performance of a neutral point clamped (NPC) three-level voltage source inverter is investigated. The inverter feeds an electric drive which is controlled by field oriented control (FOC). The improvement of the control scheme is achieved using Mamdani’s fuzzy logic controller for both rotor speed and inverter current. The main issue of this work is neutral point (NP) balancing for a three-level NPC inverter combined with a new Space Vector Pulse Width Modulation (SVPWM) algorithm. The performance of the electric system is verified via Matlab/Simulink © . The operation of the electric system is investigated in steady state and transient responses in both cases whether using or not the NP balancing algorithm. Finally, the ability of the proposed switching pattern generation algorithm for NP balancing is established.

In this paper the control scheme of a three-level three-phase inverter for grid integration of distributed generation (DG) units is investigated. Furthermore, the inverter compensates the reactive power of the load. The presented control scheme is based on instantaneous power theory in order to generate the appropriate inverter reference currents. In the outer DC bus voltage control loop and in the inner current control loop, the fuzzy logic (FL) control and the Proportional-Resonant (PR) control is applied respectively. The switching pattern generation is achieved using Space Vector Pulse Width Modulation technique. The steady state and dynamic response of the proposed electric power system has been evaluated under various operating conditions. Simulation results verify the effectiveness of the proposed control system.

This paper presents a novel control scheme for a distribution static compensator (DSTATCOM) aimed at mitigating voltage sag at the Point of Common Coupling (PCC) or eliminating current harmonics of the load. The proposed control scheme uses the d – q reference frame for the decoupling of active and reactive current components. Furthermore a selective algorithm is integrated to the control scheme in order to choose between the voltage support mode or the current harmonics elimination mode. Finally, the DSTATCOM is based on a three phase three level flying capacitor topology. The proposed control scheme outperforms the conventional one due to the ability of the suggested control system to combine multiple functions, allowing DSTATCOM to respond in various power quality issues. The effectiveness of the proposed control scheme to enhance the multifunction ability of the DSTATCOM is verified via Matlab/Simulink© in both steady state and transient response.