The Design And Research Of The Bi-directional DC/DC Converter

Green and cyclic developments of energy are becoming the burning issue inthe world. Lithium ion batteries are widely used for electric power energy storagearea and related field because of its advantage in high power density, no memoryand many times of charge and discharge. So based on lithium-ion battery, thispaper designs a high-performance bi-directional DC/DC converter withadjustable charging voltage and charge-discharging current.Firstly, paper does a detailed analysis contrasting the several topologystructures of bi-directional DC/DC converters in reference documentations, andthen paper chooses the parallel phase-shifting constituting three phaseinterleaved topology as the main circuit topology structure, which is based on bi-directional half bridge DC/DC converter topology, analyzing its advantage;Combining synchronous rectifier technology, paper analyzes in detail theoperational principle of bi-directional DC/DC converter under BUCK andBOOST models.Secondly, for determining the overall design scheme, paper chooses theconstant current and constant voltage charging way and constant currentdischarging way by analyzing the properties of charge and discharge of thelithium-ion battery and the common way of charge and discharge. Paper designabout bi-directional DC/DC converter is divided into two parts as the hardwaredesign and software design. According to the standard of the system hardwaredesign, paper realizes the design of the switch tube driving circuit and maincircuit parameters by Linear Technology’s DC/DC controller chip LTC3829andLTC3787, and realizes the PWM waveform control without MCU; According tothe characteristics of the DC/DC control chip, through multiple chip parallel tocomplete the design of three phase Interleaved topology; Paired with the powermanagement chip LTC4000, completed the constant current constant voltage regulation loop design, and combining with the characteristics of LTC4000,implements the charging voltage and charging and discharging current adjustable.In system software design, STM32F103RCT6is used as the main control chipwriting the related control program.Finally, hardware circuit is constituted in simulation software LTspice,which simulates the two work models, and then attain curve graphs describingthe process of charging and discharging. Meanwhile, the adjustability of currentand voltage can be confirmed by above simulating, which is corresponding withtheoretical analysis. The model machine designed by theoretical analysis is to bedebugged to confirm the validity in circuit topology selection, parameter designand control scheme design, which proves the validity and availability of researchfindings.