Investigation Of Quadratic Boost Converter

The utilization and development of new energy sources become a research focus because of constant serious energy crisis and environmental protection. The applications of solar photovoltaic systems, fuel cell systems, and other new energy technologies put forward higher requirements for input voltage range of switching DC-DC converter. Cascade technology for converter can effectively widen the input voltage range of switching DC-DC converter, i.e. two or more converter in cascade, but which will bring the increase number of switch tubes and complexity design of control loop with increasing number of the cascade converters.Quadratic Boost converter using only one switch tube can be realized the voltage gain related to the square of duty cycle and widen the input voltage range of switching DC-DC converter, which makes it have broad application prospect in solar photovoltaic systems, fuel cell systems and other the fields of new energy application. According to operating modes (discontinuous conduction mode, DCM and continuous conduction mode, CCM) of input inductor and energy storage inductor, quadratic Boost converter can be divided into CCM-CCM quadratic Boost converter, CCM-DCM quadratic Boost converter, DCM-CCM quadratic Boost converter and DCM-DCM quadratic Boost converter. The state space equivalent models of the four converters are established. The transfer functions of input inductor current, energy storage inductor current and output voltage to the duty cycle are derived and theirs frequency domain characteristics are analyzed, working areas of quadratic Boost converter are also divided, all of which as mention above provide a theoretical guidance for the parameter design of the converter.Energy transmission modes (ETM), output voltage ripple and controller design of quadratic Boost converter are discussed. According to the relationship between valley current of energy storage inductor and output current during switching OFF time, energy transmission modes of quadratic Boost converter and output voltage ripple characteristics are analyzed. The critical inductance value and critical operating conditions of the energy transmission modes are deduced. The feasibility of the input inductor current and output capacitor voltage used as a feedback signal of the peak current control strategy is verified, which simplifies the design of control loops.The two inductor current boundaries are derived and segmented smooth iteration mapping model of current controlled quadratic Boost converter is established depending on the detailed description of switching states. The comparative analysis of the nonlinear bifurcation behaviors is investigated with input inductor current and the storage inductor current as current feedback respectively. Two boundary conditions that shift between stable period-one state and sub-harmonic oscillation state and between DCM and CCM are derived by analyzing stability and operating mode. The operation-state regions corresponding to circuit parameter regions are estimated by utilizing the parameter-space maps. Nonlinear bifurcation behaviors, operation-state regions and stability of current controlled quadratic Boost Converter with slope compensation are analyzed. An experimental circuit is built and the results show that both different bifurcation route and operation mode shift phenomenon are changed with parameter variations, the current controlled quadratic Boost converter exhibits complicated dynamical behaviors.To extend the application range of quadratic Boost converter, the quadratic Boost converter is utilized to realize PFC in this paper. Quadratic Boost PFC converter is proposed. Comparative analysis of the advantages and disadvantages of the traditional Boost PFC converter and quadratic Boost PFC converter are investigated including input inductor current ripple, the controller design, the output voltage ripple and dynamic response. The results show that, compared with the traditional Boost PFC converter, quadratic Boost PFC converter has a smaller input inductor current ripple and faster dynamic response without increasing the complexity of the control loop.In order to verify the correctness of theoretical analysis, a lot of simulation models are builded, and corresponding experimental prototypes are set up. The experimental results are consistent with the simulation results, and the correctness of theoretical analysis is validated by simulations and experiments.