Research On Components Sharing Wide Range Resonant Converters

Resonant converters are widely used due to their advantages such as soft switching and high-power density.However,the voltage regulation range of traditional pulse frequency control single stage resonant converters is relatively narrow.Compared with single stage resonant converters,the two-stage cascaded topology has obvious advantages in voltage regulation ability and control flexibility,which is more favored in wide voltage range applications.However,the two-stage topology uses more switching devices and magnetic components,resulting in lower integration of the converter.In order to address these issues,this paper studies the components sharing methods and optimization control strategies of two-stage cascaded topology architecture.The number of converter components can be reduced and the integration is improved.In addition,the converter can achieve high efficiency over a wide voltage range.Meanwhile,the topology construction and derivation rules of components sharing are summarized,which provides new ideas for optimizing the circuit structure and performance of resonant converters.Firstly,based on a two-stage cascaded topology,a switch sharing resonant topology is proposed,which shares the bridge arms of PWM DCDC converters and resonant converters.In the switch sharing topology,the number of switches is reduced and the wide range voltage gain can be achieved.In addition,in order to achieve decoupling of the two-stage circuit,the resonant current discontinues conduction control is proposed,simplifying the converter control and design.In addition,in order to further optimize the current quality and light load efficiency,a digital adaptive frequency control is proposed,which can achieve the soft switching and optimize the inductor current ripple.Hence the overall work efficiency has been improved.Secondly,in order to further improve the integration of the converter,a switching devices and magnetic components hybrid sharing resonant topology is proposed.The coupling inductor is used to integrate the energy storage inductor,resonant inductor,and high-frequency transformer.On the basis of switching sharing,the number of magnetic components is effectively reduced.In addition,aiming at the problem that the excitation current cannot be directly sampled in hybrid sharing topology,a current sensorless adaptive frequency control is proposed.Through the designed excitation current observer,the average excitation current can be accurately estimated over a wide voltage and load range,and the optimal switching frequency can be calculated.Hence,the current ripple can be reduced and light load efficiency can be improved.Then,for applications of bidirectional power transmission such as energy storage systems,the hybrid sharing topology is further expanded,and a bidirectional switching devices and magnetic components hybrid sharing resonant converter is proposed.In addition,in view of the shortcomings for traditional control methods which require power direction detection and control logic switching,a bidirectional unified resonant current sine wave modulation is proposed.Regardless of the operating voltage and power transmission direction,the driving logic are identical,and there is no need for power direction judgment and control logic switching.Hence,the natural bidirectional power transmission can be realized.Meanwhile,the resonant current is always a sine wave without higher harmonics,which can reduce the winding loss of the magnetic components.Finally,the idea of hybrid sharing is extended to multiple combination types of PWM converter and resonant converter.Connecting different bridge cells through coupling inductors,a series of novel bidirectional resonant converter topologies suitable for the wide voltage range are derived.Combined with the proposed sine wave modulation method,the converters in the hybrid sharing topology family have the advantages of wide range voltage regulation,full range soft switching,sine wave shaped resonant current,and natural bidirectional power flow.Meanwhile,this paper deeply explores the construction and derivation of hybrid sharing topology.In addition,the operation characteristics of the converters in proposed topology family are analyzed and summarized.In response to the above research content and solutions,this paper has built corresponding experimental prototypes.And the sufficient theoretical analysis and experimental verification are provided.The experimental results prove the feasibility and effectiveness of the proposed solutions.