Research On Magnetic Integrated Boost-forward Converter

In new energy systems such as photovoltaics and fuel cells,Boost converter has important application values.The drive signal applied to the two ends of the MOSFET tube causes the switch and the diode to alternately conduct between the input inductance and the output capacitor in the boost converter.Therefore,there is equivalent to an LC filter at the output,resulting in a right half-plane zero in the transfer function of the boost converter,which will reduce the dynamic response speed of the converter.In addition,the input current ripple of the boost converter is inversely proportional to the input inductance value,which means that to achieve lower input current ripple,the input inductance must be increased.But a larger inductance value will increase the total weight of the converter and reduce the power density of the system.Current ripple will reduce the efficiency of the converter and reduce the quality of the input power supply.These shortcomings are almost fatal,especially in applications with high currents.Therefore,it is of higher practical value to study a topology or method that can eliminate the zero point of the right half plane and has higher input current stability.In order to solve the above problems,a new topology is proposed in this dissertation that can be applied to fuel cells or photovoltaic systems based on the traditional boost circuit and the circuit structure of the forward converter,which is called Magnetic integrated Boost-forward converter.This converter can not only realize the right half-plane zero point cancellation and input current ripple cancellation,but also introduce the magnetic integration technology to wind three coupled inductors on the same magnetic core in a specific form,which can reduce the volume and weight of the converter and improve power density.Aiming at right half plane zero point problem,coupled inductors are used to combine the Boost converter and the Forward converter in this dissertation.Ripple cancellation network is also added to the circuit.Compared with the traditional boost converter,the proposed topology can transfer energy to the load side through the auxiliary inductor when the input power supply is turned on,thereby eliminating the influence of right half plane zero and improving the dynamic response speed of the output voltage.To solve the problem of increased input current ripple caused by auxiliary inductance,a ripple cancellation branch composed of an inductor and a capacitor in series is added to the aforementioned circuit.By coupling with the input inductor and auxiliary inductor to offset the change in current on the input inductor,the input current remains stable.The converter can achieve lower input current ripple,thereby reducing the impact on the power supply system.The magnetic integrated module is composed of an input inductor,an auxiliary inductor and a ripple cancellation inductor.Three inductors are coupled to the same magnetic core to achieve the purpose of magnetic integration,which can reduce the weight of the system and increase the power density.Finally,a prototype with an input of 60 V and an output of 100 V and a power of 250 W was built for verification.The simulation and experimental results show that the proposed topology can achieve the elimination of the right half plane zero point and low input current ripple,and magnetic integration technology reduces the volume and weight of the converter,which improves power density.