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An asymmetric inverter features different dc-link voltages for each power cell and depending on the dc voltage ratios, there are binary, trinary, etc., asymmetric topologies. In particular, the trinary one can provide a waveform with 3^n levels, where n is the number of cells connected in cascade. Hence, for $n = 3$, an output voltage with 27 levels can be obtained, ensuring a low total harmonic distortion (THD) and reduced $dv/dt$. However, when the load consumes active power, some power cells of the inverter can operate in regeneration mode, complicating the topology and control. To overcome this problem, a new modulation method for asymmetric inverters is presented. It features an ac output voltage of 13 levels for $n = 3$, and ensures unidirectional power flow in every power cell. This new modulation method also provides a voltage waveform with low $dv/dt$ and reduced THD (5.7%). To confirm the approach, power flow and sensitivity analysis to changes in the dc voltage ratios are performed. Finally, simulation and experimental results are provided. [ABSTRACT FROM PUBLISHER]

An active power filter implemented with a four-leg voltage-source inverter using a predictive control scheme is presented. The use of a four-leg voltage-source inverter allows the compensation of current harmonic components, as well as unbalanced current generated by single-phase nonlinear loads. A detailed yet simple mathematical model of the active power filter, including the effect of the equivalent power system impedance, is derived and used to design the predictive control algorithm. The compensation performance of the proposed active power filter and the associated control scheme under steady state and transient operating conditions is demonstrated through simulations and experimental results. [ABSTRACT FROM AUTHOR]

Presents the modeling and analysis of a medium voltage current-source inverter drive. Description of the drive; Voltages in the drive system; Simulation of the drive.