Research On High Power Density Digital DC/DC Power Module

With the development of industry and national defense,the technical requirements of high-voltage-input and high-power DC/DC power module have been continuously raised in modern weaponry such as aviation,phased array radar and missiles.At the same time,the rapid development of semiconductor industry and integrated chip technology provides a good platform for the practical application of digital power module.Therefore,this paper proposes a two-stage DC/DC topology with the goal of developing a wide-input/high-voltage-output high power density digital DC/DC power module with 28V/1300W.The control adopts TI company's UCD3138A digital power control chip,and put forward the corresponding digital control optimization strategy and multi-module expansion application.First of all,this paper presents a two-stage topology that combines series-parallel front-end transformers with parallel-stage Buck circuits.The operating principle is analyzed and the parameters are designed.Through the analysis of the functional characteristics of the digital control chip used,the concept of multi-threading is introduced into the software,and the control program design based on finite state machine is proposed.The hardware design of the control circuit is described,and the design of the cascaded module with no overshoot soft start,pre-bias voltage start,constant power constant current and other functions are designed and verified.Secondly,based on the characteristics of the topology and the advantages of the numerical control platform,a number of optimized digital control strategies are added on the basis of the traditional power control strategy:1.By analyzing the influence of parasitic capacitance of the secondary side of the LLC converter by the synchronous rectifier It can not realize the phenomenon and reason of CCM,and proposed a synchronous rectifier digital control calculation method without additional sensors.2.According to the requirement of wide voltage range input,the LLC mode is designed according to the input voltage and output power,Semi-closed loop frequency conversion control strategy;3.Based on the loss analysis of Buck circuit,a variable frequency control strategy for Buck circuit is proposed in view of the wide range efficiency optimization.Finally,aiming at the application of modular extension combination,a parallel combination control system of input serial and parallel output based on multi-module is designed.A distributed control strategy based on serial master module and parallel slave module is proposed.The principle of input voltage sharing in series main system and the principle of current sharing in parallel from the system are analyzed.The stability of the system is analyzed and verified by experiments.