SRF Based Output Voltage Control of 3-Level 3-Phase 4-Leg AT-NPC Inverter

Year 2018, , 961 - 966, 01.12.2018

Emre Avcı Mehmet Uçar

https://doi.org/10.2339/politeknik.386964

Cited By: 1

Abstract

This paper proposes a synchronous reference frame (SRF) based high performance
output voltage controller for the 3-level 3-phase 4-leg (3P4L) advanced T-type
neutral point clamped (AT-NPC) inverter operated in stand-alone mode. 3-phase
inverters for stand-alone operation are required to provide 3-phase balanced
nominal voltage under different load types such as unbalanced linear and
non-linear loads. 3P4L inverters working with these types of load allow
controlling zero sequence voltage by additional fourth leg. The main
contribution of this work is the control of the 3-level 3P4L AT-NPC inverter
with an LC-type filter modeled based on the output voltage and capacitor
current feedback in the synchronous coordinate system. According to obtained
capacitor current decoupled model, double loop PI controller is adopted to control
the output voltage of the inverter. An inner capacitor current feedback loop is
employed to provide fast dynamic response and active damping of the capacitor
current. Finally, transient and steady state operation performance of the
controller have been tested with PSIM simulation studies considering different
load types. Simulation results validate that the proposed SRF based double loop
PI controller ensure high dynamic response and high quality output voltage with
less than 3% total harmonic distortion (THD) value for the 3-level 3P4L AT-NPC
inverter.

Keywords

3-level, 4-leg, AT-NPC inverter, carrier-based PWM, voltage control

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