Design And Implementation Of KW-class Full Brick DC-DC Module Power Supply

With the rapid development of the semiconductor industry and power electronics technology,switching power supplies,as an important part of the normal operation of electronic equipment,are becoming more and more popular in civilian,railway,ship,missile and aerospace applications.At the same time,changes in the precision,performance,and application scenarios of terminal equipment place increasing demands on the reliability,safety,heat dissipation performance,and power density of power supplies.In this paper,a phase-shifted full-bridge DC-DC converter is selected as the research object,with the goal of achieving stable and efficient operation of the module power supply.The magnetic component parameter calculation,thermal simulation analysis,and power supply thermal management design are completed.Based on the chip UCC28950,the research and design of control circuit and control algorithm are completed.The main research work of this paper is as follows:(1)Analyzed the basic structure,topological working principle and timing of phase-shifting control in a complete duty cycle of phase-shifted full-bridge DC-DC converters.A detailed analysis and calculation of the duty cycle loss of phase-shifted full-bridge converters and the realization of ZVS for leading leg and lagging leg,and give relevant solutions to the case where the secondary side is difficult to achieve ZVS.A Tr_lag circuit with a clamping diode on the primary side is designed to solve the voltage spike or oscillation problem of the secondary rectifier.(2)In view of the serious problem of module power dissipation under high power density,the specific parameter design scheme of the main power device of the power supply is given,and the power loss of each device is calculated and compared.The main cooling mode and heat flow path of the module power supply under operating conditions were analyzed.The thermal modeling and simulation of the power supply was completed based on the finite element analysis software,and a thermal protection circuit was designed for the module over-temperature operation.(3)The main control methods of the converter are analyzed,and the main parameters of UCC28950 are designed based on the peak current control mode.Starting from the small-signal model of the BUCK converter,the small-signal model of the phase-shifted full-bridge DC-DC converter is derived,and the control strategy and compensation network design of the closed-loop system are analyzed theoretically.A double-loop feedback network of voltage loop and current loop is designed,and the parameters of the loop are adjusted based on PI control.The correctness of the compensation network design is verified under Matlab.Based on the above analysis and calculations,a phase-shifted full-bridge DC-DC converter simulation model is built in this paper.The simulation successfully implements the phase-shifted PWM control of the primary and secondary driving signals,and the output response is good,which verifies the correctness and rationality of the system parameter calculation.Based on theoretical analysis and calculations,a full-brick module power supply with a power of 1 kW and an output voltage of 12 V was developed.Through prototype test and waveform data analysis,the power supply fully achieved ZVS,stable working performance,and conversion efficiency up to 95%.