This paper presents an energy-balance control strategy for a cascaded single-phase grid-connected H-bridge multilevel inverter linking n independent photovoltaic (PV) arrays to the grid. The control scheme is based on an energy-sampled data model of the PV system and enables the design of a voltage loop linear discrete controller for each array, ensuring the stability of the system for the whole range of PV array operating conditions. The control design is adapted to phase-shifted and level-shifted carrier pulsewidth modulations to share the control action among the cascade-connected bridges in order to concurrently synthesize a multilevel waveform and to keep each of the PV arrays at its maximum power operating point. Experimental results carried out on a seven-level inverter are included to validate the proposed approach.

A Lyapunov-based control scheme for single-phase single-stage grid-connected photovoltaic central inverters is presented. Besides rendering the closed-loop system globally stable, the designed controller is able to deal with the system uncertainty that depends on the solar irradiance. A laboratory prototype has been built as a proof of concept for the proposed control technique. A nonlinear passive adaptive controller has been programmed in a field-programmable gate array.

This paper presents a two-control loop design considering the nonlinear time-varying characteristics of a single-phase grid-connected photovoltaic (PV) full-bridge central inverter. The control scheme design is based on the energy-balance modeling of the PV system and enables the design of a voltage loop linear discrete controller ensuring the stability of the system for the whole range of PV array operating conditions. A set of experimental results carried out on a laboratory prototype is provided to validate the proposed approach.

This paper presents an energy-sampled data model of a cascade H-bridge multilevel converter for single-phase multi-string grid-connected photovoltaic systems. Based on this model a control scheme for the power converter is obtained. The achievement of the DC-AC conversion with an efficient PV energy extraction, low harmonic distortion and output unity power factor is validated with simulation results

The present work describes the analysis, modeling and control of a transformerless boost-buck power inverter used as a DC-AC power conditioning stage for grid-connected photovoltaic (PV) systems. The power conditioning system's control scheme includes a variable structure controller to assure output unity power factor and a sensorless maximum power point tracking (MPPT) algorithm to optimize the PV energy extraction. To maximize the steady-state input-output energy transfer ratio a discrete linear controller is designed from a large-signal sampled data model of the system. The achievement of the DC-AC conversion at unity power factor and the efficient PVs energy extraction are validated with simulation results.