Analysis and Development of New Switching Look-up Table for Direct Power Control of Grid Connected Three-Level NPC PWM Rectifier

Azziddin M. Razali, Nor Azizah Yusoff, Kasrul Abdul Karim, Auzani Jidin, Tole Sutikno


This paper presents a comprehensive and systematic approach in developing
a new switching look-up table for Direct Power Control (DPC) strategy
applied to the three-phase grid connected three-level Neutral-Point Clamped
(NPC) pulse width modulated (PWM) rectifier. The term of PWM rectifier
used in this paper is also known as ac-dc converter. The approach provides
detailed information regarding the effects of each multilevel converter space
vector to the distribution of input active and reactive power in the converter
system. Thus, the most optimal converter space vectors are able to be
selected by the switching look-up table, allowing smooth control of the
active and reactive powers for each sector. In addition, the proposed DPC
utilizes a NPC capacitor balanced strategy to enhance the performance of
front-end ac-dc converter during load and supply voltage disturbances. The
steady state as well as the dynamic performances of the proposed DPC are
presented and analyzed by using MATLAB Simulink software. The results
show that the ac-dc converter utilizing the new look-up table is able to
produce almost sinusoidal line currents with lower current total harmonic
distortion, unity power factor operation, adjustable dc-link output voltage
and good dynamic response during load disturbance.


Ac-to-DC converter, multilevel PWM rectifier, Direct power control, switching look-up table, neutral point clamped multilevel converter, active and reactive powers, power factor correction, capacitor balanced strategy



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