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Stabilization of multi DC bus link voltages of multilevel NPC VSI. Application to double stator induction motors

Beriber D., Talha A., Boucherit M. S.

Archives of Control Sciences

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2012

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Vol. 22, no. 1

107-120

EN

Voltage source multilevel inverters have become very attractive for power industries in power electronics applications during last years. The main purposes of studying multilevel inverters are the generation of output voltage signals with low harmonic distortion and reduction of switching frequency. An important issue of the multilevel inverter is the capacitor voltage-balancing problem. The unbalance of different DC voltage sources of multilevel neutral point clamped (NPC) voltage source inverter (VSI) constitutes the major limitation for the use of this new power converter. In this paper, we present study on the stability problem of the input DC voltages of the three-level Neutral Point Clamping (NPC) voltage source inverter (VSI). This inverter is useful for application in high voltage and high power area. In the first part, we remind the model of double stator induction motors (DSIM). Then, we develop control models of this inverter using the connection functions of the semi-conductors. We propose a Pulse Width Modulation (PWM) strategy to control this converter. The inverter is fed by constant input DC voltages. In the last part, we study the stability problem of the input DC voltages of the inverter. A cascade constituted by two three-level PWM rectifiers - two three-level NPC VSI - DSIM is discussed. The results obtained show that the input DC voltages of the inverters are not stable. To solve this problem, we propose to use a half clamping bridge. This solution is very promising in order to stabilize the input DC voltages of this converters.

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Novel digital PWM strategies of multilevel voltage source inverters

Beriber D., Talha A., Berkouk E. M., Francois B., Boucherit M. S.

Archives of Control Sciences

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2009

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Vol. 19, no. 1

43-57

EN

In this paper, two novel algorithms of algebraic PWM strategies for seven-level Neutral Point Clamped (NPC) Voltage Source Inverter (VSI) are presented. These algorithms use a control model of the inverter. In the first part, the authors develop a model of this inverter, without assumption on its control, by using design method associated to Petri nets and switching functions. In the second part, knowledge and control models of this converter are reviewed by using respectively instantaneous and continuous equivalent switching functions. In the last part, two algebraic PWM control strategies of the inverter are proposed. The obtained results are full of promise to use these digital strategies to control seven - level NPC VSI used in high voltage and high power applications as electrical traction.

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Enslavement and control in dq synchronous frame for a cascade using multilevel inverter NPC

Beriber D., Boucherit M. S., Berkouk E-M.

Archives of Control Sciences

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2008

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Vol. 18, no. 4

497-513

EN

The aim of this paper is to give a solution to unbalance problem of the input DC voltages of the nine-level NPC-VSI in dq synchronous frame. For that, we used in high voltage and great power applications, one two-level PWM current rectifier-nine-level NPC VSI-PMSM cascade. In the first part, we develop a knowledge model of the Nine-level NPC VSI and propose a space vector modulation of this converter using eight bipolar carriers. After that, this study shows particularly the problem of the stability of the DC voltages of the inverter and its consequence on the performances of the PMSM speed control. Then, we propose a solution to the problem by employed closed loop regulation using classic PI controller mode in d-q synchronous frame. We add a Clamping bridge to stabilize the eight DC input voltages of the nine-level NPC VSI. This cascade found applications in great power and high voltage fields as electrical traction.