Analysis and small-signal modelling technique for support bus DC-link of front-end coupling inductance high step-up single switch boost converter in low voltage renewable source

This study proposes a non-isolated DC converter, which is connected in series with an inverter, with a high output voltage conversion ratio for application in electricity generation systems to upgrade low-voltage to high-voltage DC. The topology of the proposed converter is based on a boost converter, which has the limitation of a low voltage conversion ratio. The converter is developed and connected using a coupling inductance technique by adding a second winding L2 coupled with the prototype winding and diode D2. This technique increases the voltage ratio via the ratio operator (N) of both the induction coils by operating a single switch at a constant frequency of 60 kHz. The working principle of the proposed converter is based on pulse width modulation with a duty cycle <= 40%. When the converter receives a low voltage DC input of 36 V, it converts the input to a high output voltage of 325 V at an output power 125 W, showing a circuit efficiency of 92.48% at full load. The synthesis and design of the controller include a linear approach to represent the parameters using the small signal methodology, which is employed to establish a transfer function. Furthermore, the proposed converter is capable of effectively regulating the output voltage, even when subjected to variations in the output load by employing a proportional-integral control mechanism. The close loop results obtained from simulations and practical implementation verified the proposed circuit design, as both results agreed with the theoretical analysis. This paper presented the high output voltage conversion ratio non-isolated DC converter, which would be applied in the electricity generation system from the substitute source, to upgrade the low-voltage to the high-voltage DC, then series connected with DC-AC inverter. The presented converter had the topology development from DC boost converter with the limitation of the low-voltage conversion ratio, which was developed and corrected with the coupling inductance technique by adding the second winding L2 to coupling with the prototype winding and diode D2. This technique could increase the higher voltage ratio via the ratio operate (N) of both induction coils, with the operating of a single switch, at the constant frequency 60 kHz. It worked according to the pulse width modulation with the duty cycle <= 40%. This converter receives low voltage input 36 VDC provide to high voltage output 325 VDC, at the output power 125 W and the circuit efficiency equal to 92.48%, at the full load. And could maintain the output voltage by PI control under changing of output loading condition. According, it were found that the obtained close loop results from simulation and implementation results verified the proposed and design circuit. Both results agreed with the theoretical analysis.