Study On Pulse Train Controlled Step-up DC/DC Converters

With the shortage of energy and environmental pollution,the development and utilization of new energy has become a research hotspot.Step-up DC/DC converter topologies with improved voltage gain and control methods for boosting converter performance are widely used in photovoltaic power generation,fuel cells,electric vehicles and etc.The pulse train control step-up DC/DC converter has a simple structure,does not need to compensate the network,and has a fast transient response speed.But when inductor current of step-up DC/DC converters operate in continuous conduction mode(CCM),the output voltage will emerge low-frequency oscillation phenomenon,which will affect the performance of the converter seriously.In this paper,the low-frequency oscillation of the output voltage of the PT-controlled CCM step-up DC/DC converter is suppressed from the DC/DC converter topology and the PT algorithm improvement.Firstly,the working principle of PT control CCM boost converter and the low frequency oscillation phenomenon are introduced in this paper.In order to improve the voltage gain of boost converter and suppress the low-frequency oscillation of the output voltage,a PT controlled converter with coupled inductor and voltage doubler cell is studied.The working principle and steady state performance of boost converter with coupled inductor and voltage doubler cell are analyzed.The mechanism of the PT controlled boost converter with coupled inductor and voltage doubler cell to suppress low frequency oscillation is discussed.Simulation and experiment show that the boost converter with coupled inductor and voltage doubler cell has higher voltage gain than the traditional boost converter,and the low frequency oscillation can be effectively suppressed by setting the circuit parameters reasonably.Secondly,a coupled inductor quadratic boost converter is proposed for the low frequency oscillation phenomenon generated by PT controlled CCM-CCM quadratic boost converter.The working principle of the coupled inductor quadratic boost converter is analyzed.The mechanism of the low frequency oscillation generated by the PT controlled CCM coupled inductor quadratic boost converter is studied.The influence of the coupled coefficient of the coupled inductor on the suppression of low frequency oscillation is discussed.The synchronous switch mapping model is established,and the coupling parameter conditions are given through numerical simulation.Finally,the theoretical analysis and the correctness of the simulation results are verified by experiments.Finally,a V~2 pulse train(Voltage-Voltage Pulse Train,V~2-PT)control method is studied for the low frequency oscillation phenomenon generated by the PT control CCM boost converter.The working principle of V~2-PT control and its mechanism of suppressing low-frequency oscillation are analyzed in detail.The parameters of the filter circuit are designed,and the synchronous switch mapping model is established.The numerical analysis is carried out by Matlab and Origin software.Simulation and experimental results verify the effectiveness of V~2-PT control in suppressing low frequency fluctuations.