This article proposes a 27-level asymmetric cascade H-bridge multilevel topology for photovoltaic applications, which considers a predictive control strategy that allows minimization of the commutations of the converter. This proposal ensures a highly sinusoidal and stable photovoltaic injection when there are solar irradiance disturbances, generating a low distortion in the current waveform and low switching losses. To validate the performance of the control and the proposed topology, the dynamic model of the alternating current (AC) and direct current (DC) side system is first obtained, which is checked by computational simulations. Subsequently, the implementation of a master–slave control is carried out, focused on the control of DC voltage and AC current. The proposal is simulated, and the total harmonic distortion (THD) is obtained in the voltage and current waveforms. Undesired commutations, typical of the predictive control, are eliminated in the AC voltage waveform, and a proper DC voltage tracking is achieved for the high-power cell. In order to demonstrate the performance of the proposed control strategy, a low-power proof-of-concept prototype is implemented, in which the energy is injected to the grid, under the event of solar irradiance disturbances (with DC control).Then, the undesired switching in the main cell is eliminated, generating THDs in the voltage and current signal of 7.76% and 2.65%, respectively.

Photovoltaic microinverters operating under rapidly varying irradiance are subject to large changes in input voltage and power flow, for which controllers designed from a single operating-point linearisation may lose their intended dynamic properties. This paper develops an exact feedback linearisation framework for a grid-connected photovoltaic microinverter equipped with a hybrid energy storage system comprising a battery and an ultracapacitor. Exact feedback linearising laws are derived for the current-control loops of the photovoltaic boost converter and of the bidirectional battery and ultracapacitor converters. An admissible operating region is obtained explicitly, ensuring that the control actions remain within modulation limits. The resulting inner-loop dynamics become independent of the operating point and of input-voltage variations. The proposed method is evaluated through detailed simulations under severe irradiance transients and is further validated on a laboratory-scale prototype. For an input-voltage step to $12.1\mathrm{V}$, the proposed controller reduces the current-tracking charge deficit from 5.72 A·ms to 0.0224 A·ms over a $5\mathrm{ms}$ interval when compared with a conventional small-signal design. During the most demanding irradiance transient, the peak-to-peak deviation of the dc-link voltage stays below 16% while the ultracapacitor supplies up to 2.8 A. The model agrees well with the experimental results at steady state and at the extremes of the dc-link, but it overestimates the transient deviation of the dc-link by 27%, the peak current of the ultracapacitor by 69%, and its switching ripple by 63%.