Modulated Predictive Voltage Control of a Four-Leg Inverter with Fixed Switching Frequency

In this paper, a novel modulated model predictive voltage control method is proposed for a two-level four-leg inverter with an output
$LC$
filter. To decouple the dynamics of state variables in an output
$LC$
filter and to improve the load voltage quality, the capacitor voltages and inductor currents are controlled simultaneously. The proposed controller predicts the state variables using the discrete-time model of LC-filtered four-leg inverter for 16 voltage vectors and evaluates them by a dual-objective cost function. The active and zero voltage vectors corresponding to the lowest cost value are realized by the three-dimensional space vector modulation, resulting in fast transient response, low steady-state error, and harmonic components centered around the fixed switching frequency. The proposed method's feasibility is confirmed through MATLAB simulation studies under balanced/unbalanced reference voltages and nonlinear loads. The performance comparison of proposed controller with the classical predictive voltage control is presented considering the transient and steady-state operating conditions.