Proportional multi‐resonant‐based controller design method enhanced with a lead compensator for stand‐alone mode three‐level three‐phase four‐leg advanced T‐NPC inverter system

Abstract

This study presents an inverter current sampled double-loop proportional multi-resonant (PMR)-based control technique for three-level (3L) three-phase four-leg (3P4L) advanced T-type neutral point clamped (AT-NPC) stand-alone mode inverter. Apart from the conventional linear controller the PMR controller has the ability to track a sinusoidal reference and does not require any axis transformation. Therefore, the main advantage of the proposed control technique for a 3P4L inverter is to independently control the output phase voltages when feeding a single phase and/or three phase loads. This is achieved by the inverter current sampled double-loop controller with a lead compensator in order to increase the control system phase margin unlike the capacitor current sampled controller. Thus, the harmonic compensation capability of the controller is increased which strengthens the controller against highly non-linear load types. The design procedures of the controller for the system are analytically explained. Then, the steady-state and dynamic performance of the controller is tested in a 3L 3P4L AT-NPC inverter system through many simulations and experimental studies. The results verify the fast-dynamic performance and the achievement of the low total harmonic distortion with a maximum of 2.89% for the 3L 3P4L AT-NPC inverter system even under serious non-linear load type.

A simplified space vector pulse width modulation method for a three‐level four‐leg inverter considering the neutral point potential balance

“…To validate the correctness analysis and verify the feasibility of the proposed 3DSVPWM for the three‐level four‐leg inverter, a model based on MATLAB/Simulink is established for simulation verification, and semiphysical simulation experiments are carried out by dSPACE‐SCALEXIO. To output a three‐phase balanced voltage when carrying unbalanced or resistance‐capacitance‐diode (RCD) loads, the inverter is controlled with double closed‐loop control in the ghγ coordinates, as shown in Figure 12, effectively uncoupling the mathematical model [24, 25]. A proportional resonance (PR) controller is used in the outer loop to filter out the third and fifth harmonics.…”

Four-Level Quasi-Nested Inverter Topology for Single-Phase Applications

“…The design of the gains corresponding to each suppressed harmonic k have effects only in the vicinity of their corresponding resonant frequency ω , if the controller bandwidth is greater than each of the rejected frequencies ω . Under this restriction k can be obtained as follows [41,42]:…”