| Developing renewable energy and increasing its share in energy consumption is one of the important measures to reduce environmental pollution and alleviate climate change,and the use of renewable energy such as solar and wind energy to generate electricity is an important way.High-gain converters are widely used in power generation systems such as solar and wind energy to solve the problems of intermittent output,low input voltage and large range of changes.Traditional BOOST converters have problems such as weak boosting capability and high devices stress,while Z-source/quasi-Z-source converters have better boost performance and have been extensively studied.In order to further improve the performance of the boosting capacity of the Z source/quasi-Z source converter,various improvements are proposed in the literatures,but it is still difficult to balance performance indicators such as the voltage-boosting capability,device stress,current ripple,and duty cycle range.Therefore,this paper proposes two high step-up interleaved converters based on the quasi-source networks,which use diode-capacitance and switching capacitor networks respectively,not only reduces device stress and input current ripple,but also has wide input voltage.In addition,the effect of coupling inductor on topology performance is analyzed,the main research content is as follows:First,the characteristics of GaN power devices are analyzed.The dynamic and static performance curves of the prototype Cascode GaN HEMT were obtained through double pulse experiments,and the performance of GaN CAVET was studied through simulation.Secondly,in order to improve the boost performance and reduce the device stress,a high-gain interleaved quasi-Z source DC/DC converter with a capacitor-diode output structure is proposed.The steady-state performance of the topology is analyzed and the voltage/current expression of the component is derived.D1 will appear intermittent under low duty cycle D,so the proposed converter has two gain expressions,and when D is greater than 0.25,it has performances such as high boost ratio,low device stress,and current sharing.Finally,the hardware circuit is designed and the above analysis is verified through simulation and experiment.Again,an improved interleaved quasi-Z source DC/DC converter using switched capacitor is proposed to reduce voltage stress of the output capacitor.This topology not only reduces the device stress and broadens the input voltage range,but also maintains the same high gain expression.Then,the two topologies mentioned in this paper are compared with other high-gain converters based on Z-source/quasi-Z-source network in the literatures,and an experimental prototype is built to verify the analysis.Finally,in order to reduce the volume and number of magnetic components,an interleaved quasi-Z source DC/DC converter using coupled inductors is proposed,which reduce the currents ripple of the input and inductor and self-inductor under the appropriate coupling coefficient.Then the equivalent inductor expressions under different working modes are deduced,and the realization method of magnetic circuit coupling and circuit coupling is analyzed.Finally,the four-coupling inductor and the two-winding inductor are wound with EI-type magnetic cores for experimental verification. |
