Design And Research Of High Power Density DC/DC Power Module Control

High power density DC / DC power modules with high voltage / wide voltage input and low voltage / high current output are widely used in weapons and equipment such as warships,phased array radar,aviation equipment,etc.With the actual application requirements,various technical indicators continue improve.At the same time,with the rapid development of the semiconductor industry,more options have been provided for the control of power modules.This paper studies a 28 V / 1200 W high power density DC / DC power module with high voltage / wide voltage input and low voltage / high current output,and proposes a two-level circuit topology;using PIC16F1708 from Microchip.The control chip and TI's UCD3138 A power supply special digital control chip perform the corresponding control design and control strategy optimization.First,this paper proposes a two-stage topology of a series-parallel LLC circuit for the front-stage transformer and a buck circuit for the rear-stage parallel.The working principle is analyzed and the main power circuit parameters are designed.Design the control circuit and software according to the selected PIC16F1708 controller.Secondly,because the area of the control circuit is limited,some functions are not easy to implement with analog control,and digital control is easier to design and implement on the control strategy.Therefore,a digital controller UCD3138 A is proposed for control.The control circuit and software are designed separately,the discrete model of the subsequent Buck circuit is established,and the stability analysis is performed according to the established model.In order to improve the dynamic response performance of the power module,the UCD3138 A digital control chip is used to propose an LLC soft start Optimization,the least square method was introduced to fit the gain curve,and the switching frequency of the LLC circuit was compensated.The improvement of dynamic response performance of this control strategy was verified by experiments.Finally,the functions of soft-start of modules under analog and digital control,parallel connection of multiple modules,and other functions were verified through experiments.The pre-biased soft-start and average current control of power modules under digital control were designed and verified by experiments.