Digital current control of the versatile buck-boost converter for photovoltaic applications

The versatile buck-boost converter has aroused interest because of its advantages such as non-inverting voltage step-up and step-down characteristic, high efficiency, wide bandwidth and regulation of input and output currents, and so forth. Hitherto, the proposed converter has been controlled by means of an analog average current control (ACC) but a digital current implementation has not been reported yet. Digital control has gained more attention due its flexibility and easy implementation. The digital current control presented in this work is based on taking more than one sample per switching period of the instantaneous current error waveform. Moreover, the proposed control allows a dead zone avoidance and mitigation that is a common problem of the non-inverting buck-boost converters. Finally, the digital current control has been tested by means of simulations to demonstrate that it can be nested with an input voltage control to perform a maximum power point tracking (MPPT) in photovoltaic applications.