Average Model-Based Feed forward and Feedback Control for PUC5 Inverter

 ABSTRACT:

This paper proposes new average model based control strategies for a 5-level Packed U-cell (PUC5) inverter in both standalone and grid-connected modes of operation. First, a simple feed forward controller (FFC) is designed, using only two pulse width modulation (PWM) carrier signals, for the PUC5 inverter operating in standalone mode. This proposed control technique ensures self-balanced operation with high steady-state performance. Moreover, the employment of the proposed FFC leads to a decrease in the capacitor's value as well as the minimization of the Total Harmonic Distortion (THD). Then, a feedback linearizing control technique is designed to improve the transient and steady-state performances. In grid-connected mode, a reduced-sensor technique based on the FFC and the state feedback (FC) techniques was applied. Simulations and experimental results are presented to prove the high performance of the proposed solutions for standalone and grid-connected operating modes.

KEYWORDS:

1.      Packed U-cell inverter

2.      PUC5

3.      Self-balancing

4.      Average model

5.      Feedback linearizing

6.      Feedforward control

7.      Power quality

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

 This work presented novel control strategies for the PUC5 inverter operating in both standalone and grid-connected modes. At a first stage, feed-forward control (FFC) was used to provide self-balancing operation of the PUC5 inverter by an appropriate selection of phase-shift between two carrier signals. The obtained current and voltage waveforms are characterized by a high-quality steady-state and slow dynamic tracking. Therefore, a nonlinear feedback control (FC) was designed to improve the transient and steady-state performances. Simulations and experimental results were provided to validate the proposed techniques. The presented results clearly show the effectiveness of both methods in maintaining a balanced capacitor voltage with high performance in tracking the reference current.

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