Research And Design Of Bi-directional DC-DC Converter For Supercapaciator

With the rise of energy storage industry,the supercapacitor as a novel energy storage component,has high energy density,high current charge and discharge,fast switching,recycling for long life,no memory effect.In photovoltaic and wind power generation system,the hybrid power new energy vehicles,Uninterruptible Power Supply(UPS)and other fields,the supercapacitor is widely used.The supercapacitor with a special charging and discharging requirements has a wide range of applications,so it is of great research value for supercapacitor bi-directional DC-DC converter.This paper studies the wide voltage range,high power,large current supercapacitor bidirectional DC-DC converter.First introduce the supercapacitor bi-directional DC-DC converter used in DC micro grid and give specific technical parameters.Design the current isolation fly-back inductor with full bridge bidirectional converter topology.To achieve a wide range of voltage mode by adding the reverse excitation inductance converter are analyzed,use a soft start and fly-back start to solve the problem of converter magnetic reset,add DC blocking capacitor to suppresses the transformer magnetic unbalanceThe hardware circuit design of the bidirectional DC-DC converter is analyzed from two parts of the main circuit and control circuit.The main circuit designs include the isolation transformer,fly-back inductor,power switch tube and so on.Additionally,transformer winding loss,fly-back inductance loss and switching tube loss are analyzed.Control circuit designs include data acquisition,hardware protection,switch tube drive,communication control.Sampling circuit realizes the real-time acquisition of voltage and current;protection circuit is implemented in the fault protection of over-current and short-circuit;drive circuit makes sure that the switch tube can reach the normal work;communication circuit helps DSP communicate with external equipment.Set up the model of small signal circuit of the converter,export system transfer function,and with the help of MATLAB SISOTOOL,design the suitable controller,and make the model of open loop frequency characteristics with suitable phase margin,good dynamic and static characteristics.Then,design the digital controller software,DSP software has the overall design and two-way control design,phase shift and bipolar PWM driver design,so that the converter can operate efficiently.Finally,through saber software simulation,the working mode of the converter and supercapacitor charging and discharging characteristics are analysized.And according to the requirements of the designs,build monitoring platform,LCD display,supercapacitor cabinet,the bi-directional DC-DC converter prototype.On the prototype,the voltage and current of the transformer,the start,stops,the output voltage and its ripple are tested.The test results verify the correctness of the theoretical analysis and the converter achieves the desired goal of designs.