Research And Design Of High Power Density Module Power Supply With Wide Voltage Input Based On Buck-Boost+LLC Integrated Topology

In many fields,such as communication,automotive,military,and aerospace,power volume and efficiency are critical parameters that must be considered when designing power supply modules.In these application areas,there is often limited space available for the power supply module,and the size of the module must be tightly controlled.Furthermore,the power module is often installed in a closed environment with poor heat dissipation conditions,leading to higher temperatures that pose additional challenges for the converter’s operating conditions.In China,the development of high voltage input and high efficiency and high power module power supply lags behind other countries,creating an urgent need to develop power supplies with wide input voltage ranges,high efficiency,and high power density.To address this need,this paper proposes a two-stage integrated Buck-Boost+LLC(BBLLC)converter with soft switching capability as the main power circuit.To reduce conduction loss in low voltage and high current scenarios,a suitable synchronous rectification strategy is designed.The paper then analyzes the working principle of the BBLLC converter and the control sequence of synchronous rectifier,and obtains the control models of voltage loop and phase shift loop.Additionally,parameters of the main power circuit are designed,including the planar transformer,magnetic components,LLC resonant cavity parameters,and power device selection.To ensure steady-state and dynamic performance of the BBLLC converter under a wide input voltage range and a wide load range,the state space average method and extended description function method are used to model the small signal of the converter,and the stability of the model is analyzed by Bode diagram.A lead corrector is designed based on the number and distribution of poles and zeros of the equivalent power stage transfer function to correct the converter control system.A double loop controller of voltage loop and phase shift loop is designed for the corrected system and is realized by digital control.A simulation model is built in Matlab-simulink to verify the effectiveness of the proposed double loop control strategy.The hardware circuit of the BBLLC module power supply prototype is then designed,including the peripheral circuit of the controller,the auxiliary source circuit,the driver circuit,and the protection circuit.The components are selected for localization.The embedded program used in Digital Signal Processor(DSP)is designed in detail,and a digital compensator is designed to compensate the loop of the converter.The digital controller is designed to realize the effective control of the steady-state precision and dynamic speed of the output voltage.The phase-shift loop control strategy is designed to realize the soft-switching of all switch tubes.Finally,based on the designed system scheme,a full-brick DC module power supply experimental prototype with 180VDC～420VDC input,28 V rated output,and maximum output power of 2k W is developed,and the peak efficiency is as high as 96.6%.