Research On Soft Switch Technology Based On 48V Vehicle DC/DC Converter

The traditional 12V power supply has some shortcomings in terms of emission standards and power performance.Most of the vehicle enterprises put forward solutions for 48V power supply.At present,phase-shifting full bridge DC/DC converter is commonly used in 48V automotive power supply,but there are some problems in this topology,such as duty cycle loss,parasitic oscillation of rectifier diode and magnetic balance of transformer.In order to solve this problem,a new type of full bridge soft switch DC/DC converter is proposed by combining the full bridge circuit with the soft switch auxiliary network.It is applied to the 48V power supply of the automobile.The specific research contents are as follows:(1)A novel full bridge soft switching DC/DC converter topology is proposed.In order to reduce the volume and weight of 48V power supply,simplify the complexity of the main circuit control strategy,and provide better power supply performance,a novel full bridge soft switching DC/DC converter topology scheme is proposed,and its working principle and soft switching characteristics are analyzed in detail in this paper.The fractional order PI~?D~?controller is used to obtain better dynamic performance.In this paper,the proposed converter is simulated by the PSIM simulation platform to verify the correctness and feasibility of the proposed scheme.The proposed topology not only overcomes many shortcomings of phase-shifting full bridge,but also simplifies the control strategy,realizes soft switching of all switching devices,and improves the working efficiency of the converter.(2)Detailed calculation of relevant parameters.In this paper,the parameter requirements of a new full bridge soft switching DC/DC converter are designed according to the design specifications.Parameter calculation and type selection design are carried out for the components in the main circuit of the converter.The design mainly includes the high frequency transformer in the full bridge circuit,as well as the resonance capacitance,clamping capacitor and coupling inductor in the auxiliary network of soft switch.Detailed parameter calculation and selection provide theoretical design guidance for the experimental prototype.(3)Design and develop the experimental prototype.Under the guidance of design parameters,a new full bridge soft switching DC/DC converter prototype is designed and developed in this paper.The hardware circuit design and program control of the prototype are described in detail.In this paper,the related waveforms of the experimental prototype results and the efficiency comparison with the classical phase-shifting full bridge DC/DC converter are analyzed to verify that the topology has the advantages of no duty cycle loss,greatly reducing the problem of transformer magnetic balance,realizing soft switching of all switch components and simplifying the control strategy difficulty.In conclusion,a new full bridge soft switching DC/DC converter is proposed based on the limitation of phase shifted full bridge DC/DC converter in this paper.In conclusion,this paper proposes a new full bridge soft switching DC/DC converter based on the limitation of phase-shifting full bridge DC/DC converter.Experimental and simulation results show that the topology not only overcomes the problems of phase-shift full bridge duty cycle loss,transformer magnetic balance and rectifier diode parasitic oscillation,but also simplifies the difficulty of control strategy,realizes the soft switching of all switch components in the converter,improves the working efficiency of the converter,and obtains better power supply performance.