New topologies of high gain-step-up dc-dc power converters for renewable energy applications
Authors:   , Alghaythi Mamdouh L. 
Published: August 2021

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] This dissertation proposes new topologies of high step-up dc-dc power electronic converters for integration renewable energy systems, such as photovoltaic panels (PV) from low voltage sources to high voltage dc buses in 480/900. The first topology presents a high step-up interleaved dc-dc converter with voltage multiplier cells and coupled inductors. The proposed converter achieves a very high step-up voltage gain due to the two coupled inductors and the voltage multiplier cell. This topology utilizes the interleaved boost converter in the input side, and the input current is shared with low ripple. Moreover, the voltage multiplier cell with the secondary windings of the coupled inductors is employed in the output side to achieve the interleaved energy storage. The voltage stress on the semiconductors switches and the passive components is significantly reduced and lower than the output voltage. The aforementioned converter can be operated without an extreme duty cycle or a high turns ratio. The operation principle of the proposed converter and the comparison between the proposed converter with other topologies are discussed. The parameters selection, and simulation results are thoroughly introduced. A 32 V to 800 V-dc is verified and simulated by using PLECS. The second topology introduces a new high voltage gain interleaved DC-DC Converter with diodes-capacitors technique and dual coupled inductors to lift a 30 V to 900 V. The input current ripple is reduced due to the interleaved dc-dc converter operation, the voltage loss on power semiconductor devices is mitigated. Furthermore, by implementing low-voltage-rated MOSFETs with a small ON-resistance, the conduction losses can be reduced, and the efficiency can be improved. The reverse recovery problem of the diodes is mitigated, and the leakage energy is recycled. The simulation results are explored. The other two proposed converters present a multiphase-interleaved boost high step-up dc-dc converter and a high voltage gain converter with an improved charge pump. Both the proposed converters offer a continuous input current, and they both operate in the continuous conduction mode. The voltage stress, the current stress and the losses on power devices are reduced with providing an ultra-voltage gain. The theoretical analysis of the aforementioned converters are analyzed with supporting simulation. The control techniques of high step-up dc-dc converters, which include the maximum power point tracking for PV applications, voltage mode control, PWM and the closed loop control response are provided. The control strategy for the dynamic performance of the aforementioned converter is presented thoroughly. The pulse width modulation (PWM) is generated by the digital signal processor (DSP) Texas Instrument TMS320F28234ZJZ. The method for designing a closed loop system includes choosing the type of control (voltage mode or current mode), generating a small signal model of the power converter, regulating the control to output transfer function of the open loop system, constructing the bode plots of the open loop system, designing voltage compensator transfer function with closed loop bode plots, and providing the simulation results.