Continuous-Input Continuous-Output Current Buck-Boost DC/DC Converters for Renewable Energy Applications: Modelling and Performance Assessment

Abstract

Stand-alone/grid connected renewable energy systems (RESs) require direct current (DC)/DC converters with continuous-input continuous-output current capabilities as maximum power point tracking (MPPT) converters. The continuous-input current feature minimizes the extracted power ripples while the continuous-output current offers non-pulsating power to the storage batteries/DC-link. CUK, D1 and D2 DC/DC converters are highly competitive candidates for this task especially because they share similar low-component count and functionality. Although these converters are of high resemblance, their performance assessment has not been previously compared. In this paper, a detailed comparison between the previously mentioned converters is carried out as several aspects should be addressed, mainly the converter tracking efficiency, conversion efficiency, inductor loss, system modelling, transient and steady-state performance. First, average model and dynamic analysis of the three converters are derived. Then, D1 and D2 small signal analysis in voltage-fed-mode is originated and compared to that of CUK in order to address the nature of converters’ response to small system changes. Finally, the effect of converters’ inductance variation on their performance is studied using rigorous simulation and experimental implementation under varying operating conditions. The assessment finally revels that D1 converter achieves the best overall efficiency with minimal inductor value.

High Performance Single-Phase Single-Stage Grid-Tied PV Current Source Inverter Using Cascaded Harmonic Compensators

“…Although CPRC and PCHC seem to achieve close performance, they differ in efficiency as well in harmonic cancellation which is tolerated to IEEE std [58][59][60].…”

“…This efficiency decreases with the increase in converter losses linearly proportional to large inductances with high copper losses [60]. On reviewing the efficiency results in Table 4, as the DC-link inductor decreased, it was expected that the efficiency decreased as well due to the expected increase in the power ripples, yet the contrary occurred for both CPRC (ζoverall.…”

“…= Output power to load RES tracked power ) is the converter ability to deliver the RES tracked power to the load. This efficiency decreases with the increase in converter losses linearly proportional to large inductances with high copper losses [60].…”

“…This leads to RES current and voltage ripples and, in consequently, delivered power ripples which deteriorate the converter MPPT performance. Another efficiency aspect must be considered, usually of equal or even more importance than the converter power conversion efficiency, typically the converter tracking efficiency [60]. The converter overall efficiency accommodates both MPPT tracking efficiency and power conversion efficiency.…”

Modified Partial-Shading-Tolerant Multi-Input-Single-Output Photovoltaic String Converter

“…For precise MPPT control of each PV independently, it is mandatory to set accurate duty cycle for each respective power electronic switch which in turn results in accurate operation and minimal oscillation in the tracked PV power. Hence, small perturbations in system variables may affect its stability and performance, thus small signal analysis method should be considered [24,34].…”